Frequencies for first 10,000 rows of pregnant variable in nhamcsopd2000 dataset :

 if female, |
 is patient |
  pregnant? |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        785        7.85        7.85
          2 |      4,166       41.66       49.51
          3 |      1,234       12.34       61.85
          4 |      3,815       38.15      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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