Frequencies for first 10,000 rows of amb22 variable in namcs1998 dataset :

 ambulatory |
       surg |
  procedure |
 #2 - 2 dgt |      Freq.     Percent        Cum.
------------+-----------------------------------
         00 |      9,982       99.82       99.82
         18 |          2        0.02       99.84
         44 |          1        0.01       99.85
         48 |          1        0.01       99.86
         57 |          1        0.01       99.87
         59 |          2        0.02       99.89
         60 |          1        0.01       99.90
         67 |          1        0.01       99.91
         83 |          1        0.01       99.92
         85 |          1        0.01       99.93
         86 |          6        0.06       99.99
         93 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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