Frequencies for first 10,000 rows of mage12 variable in natl1976 dataset :

     Age of |
     Mother |
  recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         81        0.81        0.81
          3 |        193        1.93        2.74
          4 |        356        3.56        6.30
          5 |        603        6.03       12.33
          6 |        660        6.60       18.93
          7 |        761        7.61       26.54
          8 |      3,494       34.94       61.48
          9 |      2,477       24.77       86.25
         10 |        963        9.63       95.88
         11 |        335        3.35       99.23
         12 |         71        0.71       99.94
         13 |          6        0.06      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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