Frequencies for first 10,000 rows of prov0090 variable in pos1992 dataset :

       ccpd |
certificati |
         on |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,991       99.91       99.91
          A |          5        0.05       99.96
          B |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 17 May 2017