Frequencies for first 10,000 rows of dfage variable in natl1973 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         16 |         14        0.14        0.14
         17 |         71        0.71        0.85
         18 |        168        1.68        2.53
         19 |        319        3.19        5.72
         20 |        444        4.44       10.16
         21 |        510        5.10       15.26
         22 |        547        5.47       20.73
         23 |        574        5.74       26.47
         24 |        596        5.96       32.43
         25 |        643        6.43       38.86
         26 |        597        5.97       44.83
         27 |        460        4.60       49.43
         28 |        420        4.20       53.63
         29 |        434        4.34       57.97
         30 |        381        3.81       61.78
         31 |        275        2.75       64.53
         32 |        237        2.37       66.90
         33 |        204        2.04       68.94
         34 |        169        1.69       70.63
         35 |        143        1.43       72.06
         36 |        134        1.34       73.40
         37 |        116        1.16       74.56
         38 |         94        0.94       75.50
         39 |         85        0.85       76.35
         40 |         80        0.80       77.15
         41 |         59        0.59       77.74
         42 |         68        0.68       78.42
         43 |         49        0.49       78.91
         44 |         34        0.34       79.25
         45 |         41        0.41       79.66
         46 |         29        0.29       79.95
         47 |         25        0.25       80.20
         48 |         19        0.19       80.39
         49 |          7        0.07       80.46
         50 |         12        0.12       80.58
         51 |          6        0.06       80.64
         52 |          9        0.09       80.73
         53 |          8        0.08       80.81
         54 |          6        0.06       80.87
         55 |          3        0.03       80.90
         56 |          1        0.01       80.91
         57 |          2        0.02       80.93
         58 |          2        0.02       80.95
         59 |          2        0.02       80.97
         60 |          1        0.01       80.98
         61 |          2        0.02       81.00
         62 |          1        0.01       81.01
         63 |          2        0.02       81.03
         64 |          2        0.02       81.05
         65 |          1        0.01       81.06
         66 |          1        0.01       81.07
         99 |      1,893       18.93      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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