Frequencies for first 10,000 rows of dfage variable in natl1979 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         16 |          3        0.03        0.03
         17 |         39        0.39        0.42
         18 |        115        1.15        1.57
         19 |        212        2.12        3.69
         20 |        291        2.91        6.60
         21 |        417        4.17       10.77
         22 |        462        4.62       15.39
         23 |        544        5.44       20.83
         24 |        533        5.33       26.16
         25 |        577        5.77       31.93
         26 |        550        5.50       37.43
         27 |        595        5.95       43.38
         28 |        482        4.82       48.20
         29 |        469        4.69       52.89
         30 |        403        4.03       56.92
         31 |        413        4.13       61.05
         32 |        328        3.28       64.33
         33 |        228        2.28       66.61
         34 |        184        1.84       68.45
         35 |        182        1.82       70.27
         36 |        127        1.27       71.54
         37 |        100        1.00       72.54
         38 |         89        0.89       73.43
         39 |         69        0.69       74.12
         40 |         69        0.69       74.81
         41 |         46        0.46       75.27
         42 |         34        0.34       75.61
         43 |         32        0.32       75.93
         44 |         23        0.23       76.16
         45 |         21        0.21       76.37
         46 |         14        0.14       76.51
         47 |         15        0.15       76.66
         48 |         21        0.21       76.87
         49 |         15        0.15       77.02
         50 |          4        0.04       77.06
         51 |          7        0.07       77.13
         52 |          8        0.08       77.21
         53 |          6        0.06       77.27
         54 |          4        0.04       77.31
         55 |          4        0.04       77.35
         56 |          3        0.03       77.38
         57 |          3        0.03       77.41
         58 |          2        0.02       77.43
         60 |          1        0.01       77.44
         61 |          1        0.01       77.45
         62 |          3        0.03       77.48
         64 |          1        0.01       77.49
         65 |          1        0.01       77.50
         67 |          1        0.01       77.51
         72 |          1        0.01       77.52
         80 |          1        0.01       77.53
         99 |      2,247       22.47      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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