Frequencies for first 10,000 rows of mage12 variable in natlterr1999 dataset :

     Age of |
     Mother |
  recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         72        0.72        0.72
          3 |        131        1.31        2.03
          4 |        276        2.76        4.79
          5 |        388        3.88        8.67
          6 |        549        5.49       14.16
          7 |        642        6.42       20.58
          8 |      3,198       31.98       52.56
          9 |      2,461       24.61       77.17
         10 |      1,513       15.13       92.30
         11 |        644        6.44       98.74
         12 |        122        1.22       99.96
         13 |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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