Frequencies for first 10,000 rows of dfage variable in natl1970 dataset :

     Age of |
     Father |      Freq.     Percent        Cum.
------------+-----------------------------------
         17 |         51        0.51        0.51
         18 |        160        1.60        2.11
         19 |        342        3.42        5.53
         20 |        425        4.25        9.78
         21 |        523        5.23       15.01
         22 |        622        6.22       21.23
         23 |        681        6.81       28.04
         24 |        541        5.41       33.45
         25 |        571        5.71       39.16
         26 |        546        5.46       44.62
         27 |        539        5.39       50.01
         28 |        462        4.62       54.63
         29 |        430        4.30       58.93
         30 |        371        3.71       62.64
         31 |        291        2.91       65.55
         32 |        254        2.54       68.09
         33 |        201        2.01       70.10
         34 |        194        1.94       72.04
         35 |        157        1.57       73.61
         36 |        138        1.38       74.99
         37 |        134        1.34       76.33
         38 |        103        1.03       77.36
         39 |        103        1.03       78.39
         40 |        105        1.05       79.44
         41 |         75        0.75       80.19
         42 |         67        0.67       80.86
         43 |         62        0.62       81.48
         44 |         41        0.41       81.89
         45 |         42        0.42       82.31
         46 |         36        0.36       82.67
         47 |         21        0.21       82.88
         48 |         14        0.14       83.02
         49 |         16        0.16       83.18
         50 |         14        0.14       83.32
         51 |         11        0.11       83.43
         52 |          9        0.09       83.52
         53 |          6        0.06       83.58
         54 |          8        0.08       83.66
         55 |          9        0.09       83.75
         56 |          4        0.04       83.79
         57 |          8        0.08       83.87
         58 |          3        0.03       83.90
         59 |          3        0.03       83.93
         60 |          1        0.01       83.94
         61 |          4        0.04       83.98
         62 |          4        0.04       84.02
         63 |          2        0.02       84.04
         64 |          3        0.03       84.07
         65 |          4        0.04       84.11
         66 |          2        0.02       84.13
         67 |          3        0.03       84.16
         69 |          1        0.01       84.17
         71 |          1        0.01       84.18
         88 |          1        0.01       84.19
         99 |      1,581       15.81      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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