Frequencies for first 10,000 rows of nochron variable in nhamcsed2015 dataset :

   Does patient have: None of the above |      Freq.     Percent        Cum.
----------------------------------------+-----------------------------------
                                     No |      5,052       50.52       50.52
                                    Yes |      4,782       47.82       98.34
Entire item blank, including 'None' box |        166        1.66      100.00
----------------------------------------+-----------------------------------
                                  Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 20 Nov 2017