Frequencies for first 10,000 rows of prov1410 variable in pos1991 dataset :

technologis |
 t - 90 hrs |
      + exp |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,968       99.68       99.68
          1 |         25        0.25       99.93
          2 |          4        0.04       99.97
          4 |          2        0.02       99.99
         30 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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