Frequencies for first 10,000 rows of proc9 variable in nhamcsopd2011 dataset :

Procedure 9 |      Freq.     Percent        Cum.
------------+-----------------------------------
         -9 |     10,000      100.00      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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