Frequencies for first 10,000 rows of prov1920 variable in pos1991 dataset :

        200 |
 diagnostic |
 immunology |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,536       85.36       85.36
          N |        901        9.01       94.37
          Y |        563        5.63      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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