Frequencies for first 10,000 rows of proc6 variable in nhamcsopd2009 dataset :

procedure 6 |      Freq.     Percent        Cum.
------------+-----------------------------------
         -9 |      9,999       99.99       99.99
       4525 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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