Frequencies for first 10,000 rows of diagnone variable in nhamcsopd1992 dataset :

  Diagnostic/screening services ordered |
                     or provided - None |      Freq.     Percent        Cum.
----------------------------------------+-----------------------------------
                                      0 |      7,104       71.04       71.04
                                      1 |      2,896       28.96      100.00
----------------------------------------+-----------------------------------
                                  Total |     10,000      100.00

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