Frequencies for first 10,000 rows of dfage variable in natl1996 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         15 |          1        0.01        0.01
         16 |         16        0.16        0.17
         17 |         45        0.45        0.62
         18 |         94        0.94        1.56
         19 |        176        1.76        3.32
         20 |        233        2.33        5.65
         21 |        281        2.81        8.46
         22 |        325        3.25       11.71
         23 |        360        3.60       15.31
         24 |        405        4.05       19.36
         25 |        421        4.21       23.57
         26 |        435        4.35       27.92
         27 |        442        4.42       32.34
         28 |        407        4.07       36.41
         29 |        417        4.17       40.58
         30 |        377        3.77       44.35
         31 |        404        4.04       48.39
         32 |        398        3.98       52.37
         33 |        387        3.87       56.24
         34 |        270        2.70       58.94
         35 |        268        2.68       61.62
         36 |        208        2.08       63.70
         37 |        185        1.85       65.55
         38 |        153        1.53       67.08
         39 |        142        1.42       68.50
         40 |        113        1.13       69.63
         41 |         70        0.70       70.33
         42 |         71        0.71       71.04
         43 |         37        0.37       71.41
         44 |         26        0.26       71.67
         45 |         32        0.32       71.99
         46 |         17        0.17       72.16
         47 |         16        0.16       72.32
         48 |          7        0.07       72.39
         49 |         12        0.12       72.51
         50 |         12        0.12       72.63
         51 |          8        0.08       72.71
         52 |          4        0.04       72.75
         53 |          3        0.03       72.78
         54 |          5        0.05       72.83
         55 |          3        0.03       72.86
         58 |          2        0.02       72.88
         59 |          4        0.04       72.92
         60 |          2        0.02       72.94
         61 |          1        0.01       72.95
         63 |          2        0.02       72.97
         64 |          1        0.01       72.98
         65 |          1        0.01       72.99
         66 |          1        0.01       73.00
         99 |      2,700       27.00      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015