Frequencies for first 10,000 rows of prov1570 variable in pos1991 dataset :

participati |
on medicare |
     opt/sp |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,965       99.65       99.65
          N |         35        0.35      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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