Frequencies for first 10,000 rows of vmonth variable in nhamcsed2002 dataset :

   month of |
      visit |      Freq.     Percent        Cum.
------------+-----------------------------------
    January |        795        7.95        7.95
   February |        742        7.42       15.37
      March |        774        7.74       23.11
      April |        753        7.53       30.64
        May |        846        8.46       39.10
       June |        918        9.18       48.28
       July |        941        9.41       57.69
     August |        733        7.33       65.02
  September |        694        6.94       71.96
    October |        705        7.05       79.01
   November |      1,063       10.63       89.64
   December |      1,036       10.36      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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