Frequencies for first 10,000 rows of prov1570 variable in pos1993 dataset :

participati |
on medicare |
     opt/sp |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,960       99.60       99.60
          N |         40        0.40      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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