Frequencies for first 10,000 rows of mage12 variable in natl1983 dataset :

     Age of |
     Mother |
  recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         43        0.43        0.43
          3 |        112        1.12        1.55
          4 |        232        2.32        3.87
          5 |        402        4.02        7.89
          6 |        532        5.32       13.21
          7 |        677        6.77       19.98
          8 |      3,474       34.74       54.72
          9 |      2,884       28.84       83.56
         10 |      1,213       12.13       95.69
         11 |        371        3.71       99.40
         12 |         56        0.56       99.96
         13 |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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