Frequencies for first 10,000 rows of dfage variable in natl1985 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         16 |         10        0.10        0.10
         17 |         23        0.23        0.33
         18 |         88        0.88        1.21
         19 |        174        1.74        2.95
         20 |        241        2.41        5.36
         21 |        299        2.99        8.35
         22 |        372        3.72       12.07
         23 |        441        4.41       16.48
         24 |        495        4.95       21.43
         25 |        532        5.32       26.75
         26 |        541        5.41       32.16
         27 |        537        5.37       37.53
         28 |        508        5.08       42.61
         29 |        499        4.99       47.60
         30 |        464        4.64       52.24
         31 |        385        3.85       56.09
         32 |        335        3.35       59.44
         33 |        294        2.94       62.38
         34 |        243        2.43       64.81
         35 |        206        2.06       66.87
         36 |        167        1.67       68.54
         37 |        130        1.30       69.84
         38 |        111        1.11       70.95
         39 |         71        0.71       71.66
         40 |         77        0.77       72.43
         41 |         55        0.55       72.98
         42 |         54        0.54       73.52
         43 |         39        0.39       73.91
         44 |         27        0.27       74.18
         45 |         13        0.13       74.31
         46 |          6        0.06       74.37
         47 |         10        0.10       74.47
         48 |         14        0.14       74.61
         49 |          9        0.09       74.70
         50 |          7        0.07       74.77
         51 |          1        0.01       74.78
         52 |          7        0.07       74.85
         53 |          4        0.04       74.89
         54 |          6        0.06       74.95
         55 |          2        0.02       74.97
         56 |          3        0.03       75.00
         57 |          1        0.01       75.01
         58 |          2        0.02       75.03
         59 |          5        0.05       75.08
         60 |          2        0.02       75.10
         61 |          3        0.03       75.13
         62 |          2        0.02       75.15
         63 |          1        0.01       75.16
         64 |          1        0.01       75.17
         65 |          2        0.02       75.19
         66 |          1        0.01       75.20
         67 |          3        0.03       75.23
         69 |          1        0.01       75.24
         70 |          3        0.03       75.27
         71 |          1        0.01       75.28
         74 |          1        0.01       75.29
         99 |      2,471       24.71      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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