Frequencies for first 10,000 rows of mage12 variable in natl1990 dataset :

     Age of |
     Mother |
  recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         46        0.46        0.46
          3 |        107        1.07        1.53
          4 |        220        2.20        3.73
          5 |        371        3.71        7.44
          6 |        519        5.19       12.63
          7 |        623        6.23       18.86
          8 |      3,117       31.17       50.03
          9 |      2,862       28.62       78.65
         10 |      1,555       15.55       94.20
         11 |        510        5.10       99.30
         12 |         70        0.70      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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