Frequencies for first 10,000 rows of mage12 variable in natl1969 dataset :

     Age of |
     Mother |
  recode 12 |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |         63        0.63        0.63
          3 |        126        1.26        1.89
          4 |        283        2.83        4.72
          5 |        444        4.44        9.16
          6 |        647        6.47       15.63
          7 |        769        7.69       23.32
          8 |      3,706       37.06       60.38
          9 |      2,214       22.14       82.52
         10 |      1,071       10.71       93.23
         11 |        509        5.09       98.32
         12 |        153        1.53       99.85
         13 |         15        0.15      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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