Frequencies for first 10,000 rows of dfage variable in natl1974 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         15 |          3        0.03        0.03
         16 |          5        0.05        0.08
         17 |         77        0.77        0.85
         18 |        166        1.66        2.51
         19 |        303        3.03        5.54
         20 |        409        4.09        9.63
         21 |        469        4.69       14.32
         22 |        592        5.92       20.24
         23 |        552        5.52       25.76
         24 |        656        6.56       32.32
         25 |        638        6.38       38.70
         26 |        620        6.20       44.90
         27 |        569        5.69       50.59
         28 |        404        4.04       54.63
         29 |        381        3.81       58.44
         30 |        381        3.81       62.25
         31 |        303        3.03       65.28
         32 |        235        2.35       67.63
         33 |        209        2.09       69.72
         34 |        197        1.97       71.69
         35 |        144        1.44       73.13
         36 |         96        0.96       74.09
         37 |         94        0.94       75.03
         38 |         82        0.82       75.85
         39 |         74        0.74       76.59
         40 |         60        0.60       77.19
         41 |         46        0.46       77.65
         42 |         45        0.45       78.10
         43 |         45        0.45       78.55
         44 |         45        0.45       79.00
         45 |         34        0.34       79.34
         46 |         25        0.25       79.59
         47 |         24        0.24       79.83
         48 |         14        0.14       79.97
         49 |         12        0.12       80.09
         50 |         11        0.11       80.20
         51 |         15        0.15       80.35
         52 |         12        0.12       80.47
         53 |          1        0.01       80.48
         54 |         10        0.10       80.58
         55 |          5        0.05       80.63
         56 |          3        0.03       80.66
         57 |          5        0.05       80.71
         58 |          5        0.05       80.76
         59 |          3        0.03       80.79
         61 |          1        0.01       80.80
         63 |          1        0.01       80.81
         65 |          2        0.02       80.83
         66 |          2        0.02       80.85
         68 |          1        0.01       80.86
         99 |      1,914       19.14      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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