Frequencies for first 10,000 rows of mage12 variable in natl1985 dataset :

     Age of |
     Mother |
  recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         53        0.53        0.53
          3 |        126        1.26        1.79
          4 |        216        2.16        3.95
          5 |        346        3.46        7.41
          6 |        539        5.39       12.80
          7 |        614        6.14       18.94
          8 |      3,457       34.57       53.51
          9 |      2,776       27.76       81.27
         10 |      1,414       14.14       95.41
         11 |        403        4.03       99.44
         12 |         53        0.53       99.97
         13 |          3        0.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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