Frequencies for first 10,000 rows of vmonth variable in nhamcsopd1993 dataset :

   month of |
      visit |      Freq.     Percent        Cum.
------------+-----------------------------------
    January |        852        8.52        8.52
   February |        797        7.97       16.49
      March |        687        6.87       23.36
      April |        748        7.48       30.84
        May |        860        8.60       39.44
       June |        904        9.04       48.48
       July |        794        7.94       56.42
     August |        872        8.72       65.14
  September |        687        6.87       72.01
    October |      1,393       13.93       85.94
   November |        749        7.49       93.43
   December |        657        6.57      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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