Frequencies for first 10,000 rows of amb22 variable in namcs1997 dataset :

 ambulatory |
       surg |
  procedure |
 #2 - 2 dgt |      Freq.     Percent        Cum.
------------+-----------------------------------
         00 |      9,950       99.50       99.50
         08 |          4        0.04       99.54
         18 |          1        0.01       99.55
         19 |          1        0.01       99.56
         21 |          2        0.02       99.58
         27 |          1        0.01       99.59
         29 |          1        0.01       99.60
         31 |          1        0.01       99.61
         42 |          1        0.01       99.62
         45 |          3        0.03       99.65
         54 |          1        0.01       99.66
         67 |          1        0.01       99.67
         70 |          1        0.01       99.68
         85 |          1        0.01       99.69
         86 |         18        0.18       99.87
         89 |          1        0.01       99.88
         90 |          3        0.03       99.91
         91 |          5        0.05       99.96
         93 |          2        0.02       99.98
         96 |          1        0.01       99.99
         99 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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