Frequencies for first 10,000 rows of vyear variable in namcs2010 dataset :

    year of |
      visit |      Freq.     Percent        Cum.
------------+-----------------------------------
       2009 |        220        2.20        2.20
       2010 |      9,780       97.80      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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