Frequencies for first 10,000 rows of dfage variable in natl1983 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         16 |          3        0.03        0.03
         17 |         35        0.35        0.38
         18 |         90        0.90        1.28
         19 |        182        1.82        3.10
         20 |        244        2.44        5.54
         21 |        353        3.53        9.07
         22 |        443        4.43       13.50
         23 |        458        4.58       18.08
         24 |        466        4.66       22.74
         25 |        514        5.14       27.88
         26 |        555        5.55       33.43
         27 |        562        5.62       39.05
         28 |        535        5.35       44.40
         29 |        458        4.58       48.98
         30 |        467        4.67       53.65
         31 |        355        3.55       57.20
         32 |        327        3.27       60.47
         33 |        268        2.68       63.15
         34 |        214        2.14       65.29
         35 |        207        2.07       67.36
         36 |        149        1.49       68.85
         37 |        122        1.22       70.07
         38 |         92        0.92       70.99
         39 |         87        0.87       71.86
         40 |         75        0.75       72.61
         41 |         47        0.47       73.08
         42 |         44        0.44       73.52
         43 |         32        0.32       73.84
         44 |         18        0.18       74.02
         45 |         21        0.21       74.23
         46 |         12        0.12       74.35
         47 |         18        0.18       74.53
         48 |          7        0.07       74.60
         49 |         10        0.10       74.70
         50 |          7        0.07       74.77
         51 |          6        0.06       74.83
         52 |          4        0.04       74.87
         53 |          4        0.04       74.91
         54 |          1        0.01       74.92
         55 |          5        0.05       74.97
         56 |          1        0.01       74.98
         57 |          4        0.04       75.02
         58 |          1        0.01       75.03
         59 |          2        0.02       75.05
         62 |          1        0.01       75.06
         64 |          1        0.01       75.07
         99 |      2,493       24.93      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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