Frequencies for first 10,000 rows of dfage variable in natl2001 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         15 |          3        0.03        0.03
         16 |         14        0.14        0.17
         17 |         49        0.49        0.66
         18 |        122        1.22        1.88
         19 |        188        1.88        3.76
         20 |        279        2.79        6.55
         21 |        344        3.44        9.99
         22 |        371        3.71       13.70
         23 |        373        3.73       17.43
         24 |        411        4.11       21.54
         25 |        410        4.10       25.64
         26 |        475        4.75       30.39
         27 |        463        4.63       35.02
         28 |        432        4.32       39.34
         29 |        479        4.79       44.13
         30 |        475        4.75       48.88
         31 |        420        4.20       53.08
         32 |        408        4.08       57.16
         33 |        342        3.42       60.58
         34 |        284        2.84       63.42
         35 |        261        2.61       66.03
         36 |        214        2.14       68.17
         37 |        198        1.98       70.15
         38 |        196        1.96       72.11
         39 |        119        1.19       73.30
         40 |        107        1.07       74.37
         41 |         76        0.76       75.13
         42 |         82        0.82       75.95
         43 |         51        0.51       76.46
         44 |         51        0.51       76.97
         45 |         39        0.39       77.36
         46 |         24        0.24       77.60
         47 |         16        0.16       77.76
         48 |         19        0.19       77.95
         49 |         17        0.17       78.12
         50 |         11        0.11       78.23
         51 |         10        0.10       78.33
         52 |          5        0.05       78.38
         53 |          4        0.04       78.42
         54 |          9        0.09       78.51
         55 |          3        0.03       78.54
         56 |          4        0.04       78.58
         57 |          2        0.02       78.60
         61 |          2        0.02       78.62
         63 |          1        0.01       78.63
         64 |          1        0.01       78.64
         66 |          1        0.01       78.65
         99 |      2,135       21.35      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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