Frequencies for first 10,000 rows of prov2200 variable in pos1997 dataset :

       srv: |
 laboratory |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,085       80.85       80.85
          0 |      1,183       11.83       92.68
          1 |        124        1.24       93.92
          2 |        587        5.87       99.79
          3 |         21        0.21      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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