Frequencies for first 10,000 rows of mage12 variable in natl1999 dataset :

     Age of |
     Mother |
  recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         37        0.37        0.37
          3 |        104        1.04        1.41
          4 |        185        1.85        3.26
          5 |        317        3.17        6.43
          6 |        464        4.64       11.07
          7 |        588        5.88       16.95
          8 |      3,069       30.69       47.64
          9 |      2,724       27.24       74.88
         10 |      1,734       17.34       92.22
         11 |        659        6.59       98.81
         12 |        114        1.14       99.95
         13 |          5        0.05      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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