Frequencies for first 10,000 rows of dfage variable in natl1976 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         16 |          7        0.07        0.07
         17 |         52        0.52        0.59
         18 |        169        1.69        2.28
         19 |        248        2.48        4.76
         20 |        361        3.61        8.37
         21 |        449        4.49       12.86
         22 |        525        5.25       18.11
         23 |        573        5.73       23.84
         24 |        592        5.92       29.76
         25 |        554        5.54       35.30
         26 |        634        6.34       41.64
         27 |        562        5.62       47.26
         28 |        540        5.40       52.66
         29 |        471        4.71       57.37
         30 |        304        3.04       60.41
         31 |        307        3.07       63.48
         32 |        278        2.78       66.26
         33 |        209        2.09       68.35
         34 |        183        1.83       70.18
         35 |        166        1.66       71.84
         36 |        115        1.15       72.99
         37 |         97        0.97       73.96
         38 |        102        1.02       74.98
         39 |         64        0.64       75.62
         40 |         68        0.68       76.30
         41 |         46        0.46       76.76
         42 |         36        0.36       77.12
         43 |         44        0.44       77.56
         44 |         30        0.30       77.86
         45 |         29        0.29       78.15
         46 |         18        0.18       78.33
         47 |         19        0.19       78.52
         48 |         23        0.23       78.75
         49 |         10        0.10       78.85
         50 |         10        0.10       78.95
         51 |          7        0.07       79.02
         52 |          6        0.06       79.08
         53 |          8        0.08       79.16
         54 |          3        0.03       79.19
         55 |          3        0.03       79.22
         56 |          1        0.01       79.23
         57 |          1        0.01       79.24
         58 |          1        0.01       79.25
         60 |          1        0.01       79.26
         61 |          1        0.01       79.27
         62 |          2        0.02       79.29
         63 |          1        0.01       79.30
         64 |          1        0.01       79.31
         67 |          1        0.01       79.32
         99 |      2,068       20.68      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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