Frequencies for first 10,000 rows of vmonth variable in nhamcsed1999 dataset :

   month of |
      visit |      Freq.     Percent        Cum.
------------+-----------------------------------
    January |        971        9.71        9.71
   February |        887        8.87       18.58
      March |      1,032       10.32       28.90
      April |        859        8.59       37.49
        May |        715        7.15       44.64
       June |        740        7.40       52.04
       July |        839        8.39       60.43
     August |        815        8.15       68.58
  September |        818        8.18       76.76
    October |        663        6.63       83.39
   November |        751        7.51       90.90
   December |        910        9.10      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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