Frequencies for first 10,000 rows of mage12 variable in natl1987 dataset :

     Age of |
     Mother |
  recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         70        0.70        0.70
          3 |        130        1.30        2.00
          4 |        249        2.49        4.49
          5 |        382        3.82        8.31
          6 |        475        4.75       13.06
          7 |        595        5.95       19.01
          8 |      3,227       32.27       51.28
          9 |      2,923       29.23       80.51
         10 |      1,455       14.55       95.06
         11 |        447        4.47       99.53
         12 |         46        0.46       99.99
         13 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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