Frequencies for first 10,000 rows of prov0090 variable in pos1991 dataset :

       ccpd |
certificati |
         on |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,997       99.97       99.97
          A |          2        0.02       99.99
          B |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 26 Jan 2016