Frequencies for first 10,000 rows of vyear variable in nhamcsed2003 dataset :

    year of |
      visit |      Freq.     Percent        Cum.
------------+-----------------------------------
       2002 |         43        0.43        0.43
       2003 |      9,957       99.57      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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