Frequencies for first 10,000 rows of amb variable in nhamcsopd1995 dataset :

       were |
 ambulatory |
   surgical |
      procs |
  performed |      Freq.     Percent        Cum.
------------+-----------------------------------
        Yes |        593        5.93        5.93
         No |      9,407       94.07      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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