Frequencies for first 10,000 rows of mage12 variable in natl1974 dataset :

     Age of |
     Mother |
  recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         79        0.79        0.79
          3 |        195        1.95        2.74
          4 |        398        3.98        6.72
          5 |        570        5.70       12.42
          6 |        696        6.96       19.38
          7 |        774        7.74       27.12
          8 |      3,575       35.75       62.87
          9 |      2,370       23.70       86.57
         10 |        897        8.97       95.54
         11 |        327        3.27       98.81
         12 |        112        1.12       99.93
         13 |          7        0.07      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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