Frequencies for first 10,000 rows of prov1365 variable in pos1993 dataset :

 tech super |
 - phs exam |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,993       99.93       99.93
          1 |          6        0.06       99.99
          2 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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