Frequencies for first 10,000 rows of dfage variable in natl1991 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         16 |          8        0.08        0.08
         17 |         23        0.23        0.31
         18 |         77        0.77        1.08
         19 |        156        1.56        2.64
         20 |        195        1.95        4.59
         21 |        269        2.69        7.28
         22 |        264        2.64        9.92
         23 |        343        3.43       13.35
         24 |        338        3.38       16.73
         25 |        418        4.18       20.91
         26 |        442        4.42       25.33
         27 |        459        4.59       29.92
         28 |        464        4.64       34.56
         29 |        473        4.73       39.29
         30 |        443        4.43       43.72
         31 |        409        4.09       47.81
         32 |        365        3.65       51.46
         33 |        298        2.98       54.44
         34 |        288        2.88       57.32
         35 |        213        2.13       59.45
         36 |        184        1.84       61.29
         37 |        172        1.72       63.01
         38 |        146        1.46       64.47
         39 |         86        0.86       65.33
         40 |         77        0.77       66.10
         41 |         62        0.62       66.72
         42 |         47        0.47       67.19
         43 |         44        0.44       67.63
         44 |         24        0.24       67.87
         45 |         19        0.19       68.06
         46 |         15        0.15       68.21
         47 |         12        0.12       68.33
         48 |         12        0.12       68.45
         49 |          7        0.07       68.52
         50 |          3        0.03       68.55
         51 |          3        0.03       68.58
         52 |          2        0.02       68.60
         53 |          5        0.05       68.65
         54 |          2        0.02       68.67
         55 |          1        0.01       68.68
         56 |          2        0.02       68.70
         67 |          1        0.01       68.71
         99 |      3,129       31.29      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015