Frequencies for first 10,000 rows of mage12 variable in natl1988 dataset :

     Age of |
     Mother |
  recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         53        0.53        0.53
          3 |        115        1.15        1.68
          4 |        241        2.41        4.09
          5 |        375        3.75        7.84
          6 |        502        5.02       12.86
          7 |        584        5.84       18.70
          8 |      3,233       32.33       51.03
          9 |      2,841       28.41       79.44
         10 |      1,554       15.54       94.98
         11 |        446        4.46       99.44
         12 |         55        0.55       99.99
         13 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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