Frequencies for first 10,000 rows of vmonth variable in nhamcsopd2001 dataset :

   month of |
      visit |      Freq.     Percent        Cum.
------------+-----------------------------------
    January |      1,162       11.62       11.62
   February |        794        7.94       19.56
      March |      1,158       11.58       31.14
      April |        937        9.37       40.51
        May |        774        7.74       48.25
       June |        840        8.40       56.65
       July |        847        8.47       65.12
     August |        756        7.56       72.68
  September |        586        5.86       78.54
    October |        559        5.59       84.13
   November |      1,046       10.46       94.59
   December |        541        5.41      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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