Frequencies for first 10,000 rows of amb variable in nhamcsopd1996 dataset :

       were |
 ambulatory |
   surgical |
      procs |
  performed |      Freq.     Percent        Cum.
------------+-----------------------------------
        Yes |        814        8.14        8.14
         No |      9,186       91.86      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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