Frequencies for npi variable in hcris2552_96_2011 dataset :

   national |
   provider |
 identifier |      Freq.     Percent        Cum.
------------+-----------------------------------
            |         34      100.00      100.00
------------+-----------------------------------
      Total |         34      100.00

by Jean Roth , jroth@nber.org , 2 Sep 2018