Frequencies for first 10,000 rows of proc variable in nhamcsed2013 dataset :

Were procedures provided at this visit? |      Freq.     Percent        Cum.
----------------------------------------+-----------------------------------
                                     No |      5,536       55.36       55.36
                                    Yes |      4,300       43.00       98.36
Entire item blank, including 'None' box |        164        1.64      100.00
----------------------------------------+-----------------------------------
                                  Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 7 Nov 2016