Frequencies for first 10,000 rows of vyear variable in nhamcsopd1996 dataset :

    year of |
      visit |      Freq.     Percent        Cum.
------------+-----------------------------------
         95 |        153        1.53        1.53
         96 |      9,847       98.47      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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