Frequencies for first 10,000 rows of prov2200 variable in pos1995 dataset :

       srv: |
 laboratory |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,292       82.92       82.92
          0 |      1,140       11.40       94.32
          1 |        107        1.07       95.39
          2 |        444        4.44       99.83
          3 |         17        0.17      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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