Frequencies for first 10,000 rows of rn variable in nhamcsopd2001 dataset :

    rn seen |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      4,280       42.80       42.80
          1 |      5,720       57.20      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016