Frequencies for first 10,000 rows of prov2210 variable in pos1991 dataset :

       srv: |
 laboratory |
 (clinical) |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,770       87.70       87.70
          0 |         24        0.24       87.94
          1 |        918        9.18       97.12
          2 |        229        2.29       99.41
          3 |         59        0.59      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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