Frequencies for first 10,000 rows of vmonth variable in nhamcsed1997 dataset :

   month of |
      visit |      Freq.     Percent        Cum.
------------+-----------------------------------
    January |        829        8.29        8.29
   February |        728        7.28       15.57
      March |        828        8.28       23.85
      April |        741        7.41       31.26
        May |        757        7.57       38.83
       June |        926        9.26       48.09
       July |        950        9.50       57.59
     August |        851        8.51       66.10
  September |        711        7.11       73.21
    October |      1,056       10.56       83.77
   November |        821        8.21       91.98
   December |        802        8.02      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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