Frequencies for first 10,000 rows of spiro variable in nhamcsopd2005 dataset :

spirometry/ |
  pulmonary |
   function |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,926       99.26       99.26
        yes |         74        0.74      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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