Frequencies for first 10,000 rows of copd variable in nhamcsopd2009 dataset :

       does |
patient now |
 have: copd |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,791       97.91       97.91
        yes |        209        2.09      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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