Frequencies for first 10,000 rows of pregnant variable in namcs2000 dataset :

 if female, |
 is patient |
  pregnant? |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        158        1.58        1.58
          2 |      4,857       48.57       50.15
          3 |        744        7.44       57.59
          4 |      4,241       42.41      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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