Frequencies for first 10,000 rows of dfage variable in natl1989 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         13 |          1        0.01        0.01
         16 |          5        0.05        0.06
         17 |         16        0.16        0.22
         18 |         68        0.68        0.90
         19 |        127        1.27        2.17
         20 |        180        1.80        3.97
         21 |        234        2.34        6.31
         22 |        292        2.92        9.23
         23 |        380        3.80       13.03
         24 |        442        4.42       17.45
         25 |        437        4.37       21.82
         26 |        460        4.60       26.42
         27 |        468        4.68       31.10
         28 |        507        5.07       36.17
         29 |        476        4.76       40.93
         30 |        447        4.47       45.40
         31 |        382        3.82       49.22
         32 |        346        3.46       52.68
         33 |        288        2.88       55.56
         34 |        248        2.48       58.04
         35 |        220        2.20       60.24
         36 |        200        2.00       62.24
         37 |        136        1.36       63.60
         38 |        132        1.32       64.92
         39 |        105        1.05       65.97
         40 |         89        0.89       66.86
         41 |         63        0.63       67.49
         42 |         50        0.50       67.99
         43 |         33        0.33       68.32
         44 |         30        0.30       68.62
         45 |         26        0.26       68.88
         46 |         21        0.21       69.09
         47 |         14        0.14       69.23
         48 |         12        0.12       69.35
         49 |          5        0.05       69.40
         50 |          7        0.07       69.47
         51 |          5        0.05       69.52
         52 |          4        0.04       69.56
         53 |          4        0.04       69.60
         54 |          2        0.02       69.62
         55 |          4        0.04       69.66
         56 |          3        0.03       69.69
         57 |          1        0.01       69.70
         58 |          1        0.01       69.71
         60 |          2        0.02       69.73
         63 |          1        0.01       69.74
         64 |          1        0.01       69.75
         69 |          1        0.01       69.76
         74 |          1        0.01       69.77
         99 |      3,023       30.23      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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