Frequencies for npi variable in hcris2552_96_2002 dataset :

   national |
   provider |
 identifier |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      6,197       99.98       99.98
          0 |          1        0.02      100.00
------------+-----------------------------------
      Total |      6,198      100.00

by Jean Roth , jroth@nber.org , 8 Sep 2018