Frequencies for first 10,000 rows of dfage variable in natl1986 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         12 |          1        0.01        0.01
         16 |          1        0.01        0.02
         17 |         31        0.31        0.33
         18 |         88        0.88        1.21
         19 |        142        1.42        2.63
         20 |        233        2.33        4.96
         21 |        298        2.98        7.94
         22 |        381        3.81       11.75
         23 |        421        4.21       15.96
         24 |        452        4.52       20.48
         25 |        520        5.20       25.68
         26 |        486        4.86       30.54
         27 |        494        4.94       35.48
         28 |        515        5.15       40.63
         29 |        510        5.10       45.73
         30 |        447        4.47       50.20
         31 |        380        3.80       54.00
         32 |        347        3.47       57.47
         33 |        291        2.91       60.38
         34 |        277        2.77       63.15
         35 |        214        2.14       65.29
         36 |        188        1.88       67.17
         37 |        124        1.24       68.41
         38 |        131        1.31       69.72
         39 |         96        0.96       70.68
         40 |         65        0.65       71.33
         41 |         41        0.41       71.74
         42 |         45        0.45       72.19
         43 |         45        0.45       72.64
         44 |         28        0.28       72.92
         45 |         31        0.31       73.23
         46 |         11        0.11       73.34
         47 |          9        0.09       73.43
         48 |          7        0.07       73.50
         49 |         11        0.11       73.61
         50 |          6        0.06       73.67
         51 |          6        0.06       73.73
         52 |          4        0.04       73.77
         53 |          5        0.05       73.82
         54 |          1        0.01       73.83
         55 |          2        0.02       73.85
         56 |          1        0.01       73.86
         57 |          1        0.01       73.87
         60 |          1        0.01       73.88
         61 |          3        0.03       73.91
         62 |          1        0.01       73.92
         75 |          1        0.01       73.93
         76 |          1        0.01       73.94
         99 |      2,606       26.06      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 3 Jan 2016