Frequencies for first 10,000 rows of prov4180 variable in pos2006 dataset :

  number of |
  lab sites |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |     10,000      100.00      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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