Frequencies for first 10,000 rows of mage12 variable in natl1972 dataset :

     Age of |
     Mother |
  recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         74        0.74        0.74
          3 |        179        1.79        2.53
          4 |        321        3.21        5.74
          5 |        554        5.54       11.28
          6 |        672        6.72       18.00
          7 |        801        8.01       26.01
          8 |      3,739       37.39       63.40
          9 |      2,199       21.99       85.39
         10 |        922        9.22       94.61
         11 |        420        4.20       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