Frequencies for first 10,000 rows of amb variable in nhamcsopd1999 dataset :

       were |
 ambulatory |
   surgical |
      procs |
 performed? |      Freq.     Percent        Cum.
------------+-----------------------------------
         No |      9,376       93.76       93.76
        Yes |        624        6.24      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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