NEW:

As reported by lvl78 player, one needs around 55k - 60k exp per 0.01%
What means that lvl 78-79 is around 550m - 600m exp.

CONGRATULAIONS TO NCSOFT FOR MAKING A GAME WITH THE UBER CONTENT and INTERESTING GAMEPLAY ! /sarcasm off

Values accurate to - [0 ; 1000] exp
Last column: how many mobs of level N you have to kill at level N to get to the next level (20% field bonus not factored)

lvl       exp          % increase     exp difference   % inc per diff      mobs exp   exp inc   to kill to next (1 x hp mobs)
                                                                                                           
13:       141 194                                                           381                    132   
14:       191 458      35.60%              50 264                           411        7.87%       153   
15:       254 425      32.89%              62 967           25.27%          441        7.30%       176   
16:       331 951      30.47%              77 526           23.12%          471        6.80%       200   
17:       426 295      28.42%              94 344           21.69%          499        5.94%       228   
18:       540 048      26.68%             113 753           20.57%          528        5.81%       257   
19:       675 648      25.11%             135 600           19.21%          559        5.87%       287   
20:       835 948      23.73%             160 300           18.22%          588        5.19%       320   
21:     1 023 824      22.47%             187 876           17.20%          630        7.14%       347   
22:     1 242 699      21.38%             218 875           16.50%          677        7.46%       373   
23:     1 495 552      20.35%             252 853           15.52%          724        6.94%       402   
24:     1 786 380      19.45%             290 828           15.02%          771        6.49%       431   
25:     2 118 882      18.61%             332 502           14.33%          818        6.10%       462   
26:     2 497 097      17.85%             378 215           13.75%          872        6.60%       491   
27:     2 925 271      17.15%             428 174           13.21%          918        5.28%       526   
28:     3 408 396      16.52%             483 125           12.83%          972        5.88%       557   
29:     3 949 767      15.88%             541 371           12.06%          1026       5.56%       591   
30:     4 555 828      15.34%             606 061           11.95%          1080       5.26%       625   
31:     5 231 305      14.83%             675 477           11.45%          1153       6.76%       651   
32:     5 981 605      14.34%             750 300           11.08%          1228       6.50%       677   
33:     6 812 515      13.89%             830 910           10.74%          1306       6.35%       703   
34:     7 730 051      13.47%             917 536           10.43%          1387       6.20%       729   
35:     8 740 907      13.08%           1 010 856           10.17%          1470       5.98%       755   
36:     9 850 187      12.69%           1 109 280            9.74%          1555       5.78%       782   
37:    11 066 140      12.34%           1 215 953            9.62%          1642       5.59%       809   
38:    12 395 264      12.01%           1 329 124            9.31%          1732       5.48%       837   
39:    13 844 960      11.70%           1 449 696            9.07%          1825       5.37%       865   
40:    15 423 369      11.40%           1 578 409            8.88%          1920       5.21%       893   
41:    17 137 140      11.11%           1 713 771            8.58%          2017       5.05%       922   
42:    18 996 129      10.85%           1 858 989            8.47%          2116       4.91%       950   
43:    21 007 221      10.59%           2 011 092            8.18%          2218       4.82%       980   
44:    23 180 959      10.35%           2 173 738            8.09%          2323       4.73%     1 009  
45:    25 525 263      10.11%           2 344 304            7.85%          2430       4.61%     1 039  
46:    28 050 055       9.89%           2 524 792            7.70%          2539       4.49%     1 069  
47:    30 764 795       9.68%           2 714 740            7.52%          2650       4.37%     1 100  
48:    33 680 443       9.48%           2 915 648            7.40%          2764       4.30%     1 131  
49:    36 806 677       9.28%           3 126 234            7.22%          2881       4.23%     1 162  
50:    40 154 423       9.10%           3 347 746            7.09%          3000       4.13%     1 790  
51:    45 525 173      13.38% (wall)    5 370 750           60.43%          3121       4.03%     1 838  
52:    51 262 908      12.60%           5 737 735            6.83%          3244       3.94%     1 887  
53:    57 384 245      11.94%           6 121 337            6.69%          3370       3.88%     1 936  
54:    63 908 253      11.37%           6 524 008            6.58%          3499       3.83%     1 985  
55:    70 853 197      10.87%           6 944 944            6.45%          3630       3.74%     2 713  
56:    80 701 533      13.90% (wall)    9 848 336           41.81%          3763       3.66%     2 780  
57:    91 162 927      12.96%          10 461 394            6.22%          3898       3.59%     2 848  
58:   102 265 903      12.18%          11 102 976            6.13%          4036       3.54%     2 917  
59:   114 038 919      11.51%          11 773 016            6.03%          4177       3.49%     2 986  
60:   126 509 802      10.94%          12 470 883            5.93%          4320       3.42%     4 583  
61:   146 309 168      15.65% (wall)   19 799 366           58.76%          4466       3.38%     4 688  
62:   167 245 000      14.31%          20 935 832            5.74%                              
63:   189 365 000      13.23%          22 120 000            5.66% 
64:   212 718 573      12.33%          23 353 573            5.58% 
65:   237 352 649      11.58%          24 634 076            5.48% 
66:   271 975 692      14.59% (wall)   34 623 043           40.55%
67:   308 443 489      13.41%          36 467 797            5.33% 
68:   346 827 294      12.44%          38 383 805            5.25% 
69:   387 199 711      11.64%          40 372 417            5.18% 
70:   429 634 526      10.96%          42 434 815            5.11% 
71:   474 211 049      10.38%          44 576 523            5.05% 
72:   532 696 134      12.33%          58 485 085           31.20%
73:   606 324 800      13.82%          73 628 666           25.89%
74:   696 381 827      14.85%          90 057 027           22.31%
75:   804 230 838      15.49%         107 849 011           19.76%
76:   931 282 188      15.80%         127 051 350           17.80%

estimations

77: 1 207 649 755      29.68%         149 000 000          117.52%
78: 1 633 333 538      35.25%         258 000 000           54.03%
79: 2 208 333 538      35.20%         575 000 000           35.08%