Frequencies for first 10,000 rows of dfage variable in natl1987 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         16 |          3        0.03        0.03
         17 |         29        0.29        0.32
         18 |         64        0.64        0.96
         19 |        129        1.29        2.25
         20 |        215        2.15        4.40
         21 |        254        2.54        6.94
         22 |        361        3.61       10.55
         23 |        385        3.85       14.40
         24 |        426        4.26       18.66
         25 |        511        5.11       23.77
         26 |        522        5.22       28.99
         27 |        530        5.30       34.29
         28 |        505        5.05       39.34
         29 |        506        5.06       44.40
         30 |        440        4.40       48.80
         31 |        341        3.41       52.21
         32 |        323        3.23       55.44
         33 |        313        3.13       58.57
         34 |        229        2.29       60.86
         35 |        208        2.08       62.94
         36 |        163        1.63       64.57
         37 |        132        1.32       65.89
         38 |        131        1.31       67.20
         39 |        102        1.02       68.22
         40 |         68        0.68       68.90
         41 |         47        0.47       69.37
         42 |         58        0.58       69.95
         43 |         36        0.36       70.31
         44 |         25        0.25       70.56
         45 |         19        0.19       70.75
         46 |         23        0.23       70.98
         47 |          9        0.09       71.07
         48 |          9        0.09       71.16
         49 |          9        0.09       71.25
         50 |          6        0.06       71.31
         51 |          7        0.07       71.38
         52 |          3        0.03       71.41
         53 |          1        0.01       71.42
         54 |          3        0.03       71.45
         55 |          1        0.01       71.46
         56 |          2        0.02       71.48
         57 |          4        0.04       71.52
         59 |          1        0.01       71.53
         60 |          1        0.01       71.54
         61 |          2        0.02       71.56
         62 |          1        0.01       71.57
         64 |          1        0.01       71.58
         74 |          1        0.01       71.59
         99 |      2,841       28.41      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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