Frequencies for first 10,000 rows of dfage variable in natl1981 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         16 |          8        0.08        0.08
         17 |         30        0.30        0.38
         18 |         85        0.85        1.23
         19 |        158        1.58        2.81
         20 |        299        2.99        5.80
         21 |        361        3.61        9.41
         22 |        427        4.27       13.68
         23 |        526        5.26       18.94
         24 |        562        5.62       24.56
         25 |        580        5.80       30.36
         26 |        526        5.26       35.62
         27 |        530        5.30       40.92
         28 |        563        5.63       46.55
         29 |        448        4.48       51.03
         30 |        416        4.16       55.19
         31 |        395        3.95       59.14
         32 |        334        3.34       62.48
         33 |        309        3.09       65.57
         34 |        236        2.36       67.93
         35 |        157        1.57       69.50
         36 |        143        1.43       70.93
         37 |        108        1.08       72.01
         38 |        116        1.16       73.17
         39 |         76        0.76       73.93
         40 |         57        0.57       74.50
         41 |         37        0.37       74.87
         42 |         30        0.30       75.17
         43 |         40        0.40       75.57
         44 |         22        0.22       75.79
         45 |         22        0.22       76.01
         46 |         24        0.24       76.25
         47 |         10        0.10       76.35
         48 |         12        0.12       76.47
         49 |          7        0.07       76.54
         50 |         10        0.10       76.64
         51 |          2        0.02       76.66
         52 |          1        0.01       76.67
         53 |          3        0.03       76.70
         54 |          3        0.03       76.73
         55 |          1        0.01       76.74
         56 |          4        0.04       76.78
         57 |          2        0.02       76.80
         58 |          4        0.04       76.84
         59 |          1        0.01       76.85
         60 |          1        0.01       76.86
         61 |          3        0.03       76.89
         64 |          3        0.03       76.92
         66 |          1        0.01       76.93
         99 |      2,307       23.07      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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