Frequencies for first 10,000 rows of pregnant variable in nhamcsed2000 dataset :

 if female, |
 is patient |
  pregnant? |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        282        2.82        2.82
          2 |      3,294       32.94       35.76
          3 |      1,607       16.07       51.83
          4 |      4,817       48.17      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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