Frequencies for first 10,000 rows of dfage variable in natl1982 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         15 |          1        0.01        0.01
         16 |          2        0.02        0.03
         17 |         29        0.29        0.32
         18 |         86        0.86        1.18
         19 |        180        1.80        2.98
         20 |        247        2.47        5.45
         21 |        373        3.73        9.18
         22 |        395        3.95       13.13
         23 |        506        5.06       18.19
         24 |        518        5.18       23.37
         25 |        586        5.86       29.23
         26 |        542        5.42       34.65
         27 |        568        5.68       40.33
         28 |        525        5.25       45.58
         29 |        428        4.28       49.86
         30 |        417        4.17       54.03
         31 |        372        3.72       57.75
         32 |        333        3.33       61.08
         33 |        279        2.79       63.87
         34 |        260        2.60       66.47
         35 |        219        2.19       68.66
         36 |        143        1.43       70.09
         37 |        122        1.22       71.31
         38 |         85        0.85       72.16
         39 |         88        0.88       73.04
         40 |         54        0.54       73.58
         41 |         53        0.53       74.11
         42 |         42        0.42       74.53
         43 |         23        0.23       74.76
         44 |         25        0.25       75.01
         45 |         17        0.17       75.18
         46 |         13        0.13       75.31
         47 |         12        0.12       75.43
         48 |          7        0.07       75.50
         49 |         10        0.10       75.60
         50 |          3        0.03       75.63
         51 |          7        0.07       75.70
         52 |          6        0.06       75.76
         53 |          3        0.03       75.79
         54 |          5        0.05       75.84
         55 |          4        0.04       75.88
         56 |          2        0.02       75.90
         57 |          2        0.02       75.92
         58 |          2        0.02       75.94
         59 |          2        0.02       75.96
         62 |          2        0.02       75.98
         63 |          1        0.01       75.99
         64 |          1        0.01       76.00
         66 |          1        0.01       76.01
         68 |          1        0.01       76.02
         73 |          1        0.01       76.03
         86 |          1        0.01       76.04
         99 |      2,396       23.96      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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