Frequencies for first 10,000 rows of prov2420 variable in pos1991 dataset :

       srv: |
psychologic |
         al |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,965       99.65       99.65
          0 |         10        0.10       99.75
          1 |          4        0.04       99.79
          2 |         10        0.10       99.89
          3 |         11        0.11      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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