Frequencies for first 10,000 rows of vmonth variable in nhamcsopd1998 dataset :

   month of |
      visit |      Freq.     Percent        Cum.
------------+-----------------------------------
    January |        871        8.71        8.71
   February |        501        5.01       13.72
      March |        958        9.58       23.30
      April |      1,042       10.42       33.72
        May |        795        7.95       41.67
       June |        950        9.50       51.17
       July |        750        7.50       58.67
     August |        540        5.40       64.07
  September |      1,188       11.88       75.95
    October |        946        9.46       85.41
   November |        656        6.56       91.97
   December |        803        8.03      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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