Frequencies for first 10,000 rows of amb variable in nhamcsopd2002 dataset :

       were |
   surgical |
 procedures |
  ord/sched |
   or perf? |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,258       92.58       92.58
          1 |        742        7.42      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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