Frequencies for ndc variable in nadacc20160727 dataset :

   National |
  Drug Code |
      (NDC) |      Freq.     Percent        Cum.
------------+-----------------------------------
00002751001 |          1        3.70        3.70
00002751017 |          1        3.70        7.41
00002751101 |          1        3.70       11.11
00002751201 |          1        3.70       14.81
00002751659 |          1        3.70       18.52
00002771227 |          1        3.70       22.22
00002803101 |          1        3.70       25.93
00002821501 |          1        3.70       29.63
00002821517 |          1        3.70       33.33
00002831501 |          1        3.70       37.04
00002831517 |          1        3.70       40.74
00002850101 |          1        3.70       44.44
00002871501 |          1        3.70       48.15
00002871517 |          1        3.70       51.85
00002879759 |          1        3.70       55.56
00002879859 |          1        3.70       59.26
00002879959 |          1        3.70       62.96
00002880359 |          1        3.70       66.67
00002880559 |          1        3.70       70.37
00378967130 |          1        3.70       74.07
52427027430 |          1        3.70       77.78
55513007330 |          1        3.70       81.48
55513007430 |          1        3.70       85.19
55513007530 |          1        3.70       88.89
55513071001 |          1        3.70       92.59
59630077703 |          1        3.70       96.30
62175031237 |          1        3.70      100.00
------------+-----------------------------------
      Total |         27      100.00

by Jean Roth , jroth@nber.org , 10 Feb 2018