Frequencies for first 10,000 rows of pregtest variable in nhamcsopd2003 dataset :

  pregnancy |
       test |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,959       99.59       99.59
        yes |         41        0.41      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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