Frequencies for first 10,000 rows of mage12 variable in natl1979 dataset :

     Age of |
     Mother |
  recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         58        0.58        0.58
          3 |        163        1.63        2.21
          4 |        318        3.18        5.39
          5 |        470        4.70       10.09
          6 |        599        5.99       16.08
          7 |        703        7.03       23.11
          8 |      3,617       36.17       59.28
          9 |      2,569       25.69       84.97
         10 |      1,113       11.13       96.10
         11 |        309        3.09       99.19
         12 |         78        0.78       99.97
         13 |          3        0.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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