Frequencies for first 10,000 rows of pregnant variable in nhamcsopd2005 dataset :

 if female, is |
       patient |
     pregnant? |      Freq.     Percent        Cum.
---------------+-----------------------------------
           yes |        809        8.09        8.09
            no |      4,590       45.90       53.99
       unknown |        437        4.37       58.36
not applicable |      3,952       39.52       97.88
         blank |        212        2.12      100.00
---------------+-----------------------------------
         Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016