Frequencies for first 10,000 rows of prov1410 variable in pos1993 dataset :

technologis |
 t - 90 hrs |
      + exp |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,974       99.74       99.74
          1 |         20        0.20       99.94
          2 |          3        0.03       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