Frequencies for first 10,000 rows of proc variable in nhamcsed2000 dataset :

       were |
 procedures |
  provided? |      Freq.     Percent        Cum.
------------+-----------------------------------
         No |      5,509       55.09       55.09
        Yes |      4,219       42.19       97.28
  No answer |        272        2.72      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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