Frequencies for first 10,000 rows of mage12 variable in natl1971 dataset :

     Age of |
     Mother |
  recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         54        0.54        0.54
          3 |        151        1.51        2.05
          4 |        305        3.05        5.10
          5 |        481        4.81        9.91
          6 |        607        6.07       15.98
          7 |        765        7.65       23.63
          8 |      3,904       39.04       62.67
          9 |      2,230       22.30       84.97
         10 |        956        9.56       94.53
         11 |        402        4.02       98.55
         12 |        139        1.39       99.94
         13 |          6        0.06      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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