Frequencies for first 10,000 rows of nochron variable in nhamcsed2014 dataset :

   Does patient have: None of the above |      Freq.     Percent        Cum.
----------------------------------------+-----------------------------------
                                     No |      4,569       45.69       45.69
                                    Yes |      5,370       53.70       99.39
Entire item blank, including 'None' box |         61        0.61      100.00
----------------------------------------+-----------------------------------
                                  Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 11 Apr 2017