Frequencies for first 10,000 rows of dfage variable in natl1969 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         17 |         60        0.60        0.60
         18 |        136        1.36        1.96
         19 |        269        2.69        4.65
         20 |        413        4.13        8.78
         21 |        602        6.02       14.80
         22 |        635        6.35       21.15
         23 |        543        5.43       26.58
         24 |        617        6.17       32.75
         25 |        617        6.17       38.92
         26 |        575        5.75       44.67
         27 |        488        4.88       49.55
         28 |        423        4.23       53.78
         29 |        389        3.89       57.67
         30 |        354        3.54       61.21
         31 |        305        3.05       64.26
         32 |        282        2.82       67.08
         33 |        215        2.15       69.23
         34 |        207        2.07       71.30
         35 |        184        1.84       73.14
         36 |        151        1.51       74.65
         37 |        135        1.35       76.00
         38 |        135        1.35       77.35
         39 |        108        1.08       78.43
         40 |        118        1.18       79.61
         41 |         79        0.79       80.40
         42 |         67        0.67       81.07
         43 |         49        0.49       81.56
         44 |         42        0.42       81.98
         45 |         45        0.45       82.43
         46 |         38        0.38       82.81
         47 |         24        0.24       83.05
         48 |         26        0.26       83.31
         49 |         21        0.21       83.52
         50 |         15        0.15       83.67
         51 |         13        0.13       83.80
         52 |         11        0.11       83.91
         53 |         13        0.13       84.04
         54 |         14        0.14       84.18
         55 |          8        0.08       84.26
         56 |          9        0.09       84.35
         57 |          6        0.06       84.41
         58 |          5        0.05       84.46
         59 |          5        0.05       84.51
         60 |          5        0.05       84.56
         61 |          2        0.02       84.58
         62 |          1        0.01       84.59
         63 |          1        0.01       84.60
         64 |          1        0.01       84.61
         65 |          5        0.05       84.66
         66 |          2        0.02       84.68
         67 |          1        0.01       84.69
         68 |          1        0.01       84.70
         69 |          1        0.01       84.71
         70 |          1        0.01       84.72
         71 |          1        0.01       84.73
         73 |          2        0.02       84.75
         82 |          3        0.03       84.78
         99 |      1,522       15.22      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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