Frequencies for first 10,000 rows of pregnant variable in namcs2012 dataset :

    Is patient |
     pregnant? |      Freq.     Percent        Cum.
---------------+-----------------------------------
         Blank |      3,836       38.36       38.36
Not applicable |      4,248       42.48       80.84
           Yes |        339        3.39       84.23
            No |      1,577       15.77      100.00
---------------+-----------------------------------
         Total |     10,000      100.00

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