Frequencies for first 10,000 rows of prov2200 variable in pos1991 dataset :

       srv: |
 laboratory |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,416       84.16       84.16
          0 |      1,233       12.33       96.49
          1 |         57        0.57       97.06
          2 |        290        2.90       99.96
          3 |          4        0.04      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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