Frequencies for first 10,000 rows of prov1350 variable in pos1993 dataset :

 tech super |
          - |
microbiolog |
          y |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,789       97.89       97.89
          1 |        166        1.66       99.55
          2 |         39        0.39       99.94
          3 |          2        0.02       99.96
          4 |          2        0.02       99.98
          5 |          2        0.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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