Frequencies for first 10,000 rows of vyear variable in nhamcsed2005 dataset :

    year of |
      visit |      Freq.     Percent        Cum.
------------+-----------------------------------
       2004 |        137        1.37        1.37
       2005 |      9,863       98.63      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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