Frequencies for first 10,000 rows of pregnant variable in namcs1997 dataset :

 if female, |
 is patient |
  pregnant? |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |        206        2.06        2.06
          2 |      4,944       49.44       51.50
          3 |        648        6.48       57.98
          4 |      4,202       42.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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