Frequencies for first 10,000 rows of proc variable in nhamcsed1998 dataset :

       were |
 procedures |
  provided? |      Freq.     Percent        Cum.
------------+-----------------------------------
         No |      5,604       56.04       56.04
        Yes |      4,380       43.80       99.84
  No answer |         16        0.16      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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