Frequencies for first 10,000 rows of prov2420 variable in pos1997 dataset :

       srv: |
psychologic |
         al |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,933       99.33       99.33
          0 |         16        0.16       99.49
          1 |         18        0.18       99.67
          2 |         15        0.15       99.82
          3 |         18        0.18      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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