Frequencies for first 10,000 rows of mage12 variable in natl1978 dataset :

     Age of |
     Mother |
  recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         73        0.73        0.73
          3 |        153        1.53        2.26
          4 |        350        3.50        5.76
          5 |        504        5.04       10.80
          6 |        597        5.97       16.77
          7 |        649        6.49       23.26
          8 |      3,599       35.99       59.25
          9 |      2,522       25.22       84.47
         10 |      1,165       11.65       96.12
         11 |        325        3.25       99.37
         12 |         59        0.59       99.96
         13 |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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