Frequencies for first 10,000 rows of prov2200 variable in pos2004 dataset :

       srv: |
 laboratory |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      7,482       74.82       74.82
          0 |      1,345       13.45       88.27
          1 |        153        1.53       89.80
          2 |        981        9.81       99.61
          3 |         39        0.39      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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