Frequencies for first 10,000 rows of mage12 variable in natl1989 dataset :

     Age of |
     Mother |
  recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         46        0.46        0.46
          3 |        112        1.12        1.58
          4 |        220        2.20        3.78
          5 |        396        3.96        7.74
          6 |        498        4.98       12.72
          7 |        570        5.70       18.42
          8 |      3,111       31.11       49.53
          9 |      2,873       28.73       78.26
         10 |      1,584       15.84       94.10
         11 |        500        5.00       99.10
         12 |         86        0.86       99.96
         13 |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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