Frequencies for first 10,000 rows of prov1340 variable in pos1995 dataset :

 tech super |
          - |
immunohemat |
      ology |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,860       98.60       98.60
          1 |        113        1.13       99.73
          2 |         23        0.23       99.96
          3 |          2        0.02       99.98
          4 |          2        0.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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