Frequencies for first 10,000 rows of prov1400 variable in pos1993 dataset :

technologis |
        t - |
proficiency |
       exam |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,929       99.29       99.29
          1 |         55        0.55       99.84
          2 |          7        0.07       99.91
          3 |          4        0.04       99.95
          4 |          1        0.01       99.96
          6 |          1        0.01       99.97
          8 |          2        0.02       99.99
          9 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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