Frequencies for first 10,000 rows of rf_inftr variable in natl2013 dataset :

Infertility |
  Treatment |
        RFP |
590=f_rf_in |
   ft_drg R |      Freq.     Percent        Cum.
------------+-----------------------------------
          N |      9,747       97.47       97.47
          U |        167        1.67       99.14
          Y |         86        0.86      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015