Frequencies for first 10,000 rows of amb2 variable in nhamcsopd2000 dataset :

 ambulatory |
   surgical |
  procedure |
         #2 |      Freq.     Percent        Cum.
------------+-----------------------------------
       0000 |      9,952       99.52       99.52
       0331 |          1        0.01       99.53
       0391 |          1        0.01       99.54
       1371 |          1        0.01       99.55
       2188 |          1        0.01       99.56
       4292 |          1        0.01       99.57
       4523 |          1        0.01       99.58
       4903 |          1        0.01       99.59
       5110 |          1        0.01       99.60
       5732 |          2        0.02       99.62
       6632 |          1        0.01       99.63
       6711 |          1        0.01       99.64
       672- |          1        0.01       99.65
       6909 |          1        0.01       99.66
       7021 |          1        0.01       99.67
       7534 |          3        0.03       99.70
       7569 |          1        0.01       99.71
       7709 |          1        0.01       99.72
       7932 |          1        0.01       99.73
       8086 |          1        0.01       99.74
       8602 |          1        0.01       99.75
       8611 |          2        0.02       99.77
       8628 |          1        0.01       99.78
       863- |          5        0.05       99.83
       8659 |          2        0.02       99.85
       8669 |          2        0.02       99.87
       8839 |          2        0.02       99.89
       8915 |          1        0.01       99.90
       9335 |          1        0.01       99.91
       9357 |          2        0.02       99.93
       9359 |          1        0.01       99.94
       9659 |          2        0.02       99.96
       9738 |          2        0.02       99.98
       9999 |          2        0.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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