Frequencies for first 10,000 rows of popvism variable in namcs1993 dataset :

  estimated |
   provider |
      visit |
     volume |
   (masked) |      Freq.     Percent        Cum.
------------+-----------------------------------
         -1 |      4,557       45.57       45.57
          0 |      5,443       54.43      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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