Frequencies for first 10,000 rows of mage12 variable in natl1997 dataset :

     Age of |
     Mother |
  recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         51        0.51        0.51
          3 |        113        1.13        1.64
          4 |        226        2.26        3.90
          5 |        360        3.60        7.50
          6 |        486        4.86       12.36
          7 |        563        5.63       17.99
          8 |      2,965       29.65       47.64
          9 |      2,751       27.51       75.15
         10 |      1,712       17.12       92.27
         11 |        660        6.60       98.87
         12 |        109        1.09       99.96
         13 |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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