Frequencies for first 10,000 rows of vmonth variable in nhamcsopd2008 dataset :

   month of |
      visit |      Freq.     Percent        Cum.
------------+-----------------------------------
    january |        832        8.32        8.32
   february |        595        5.95       14.27
      march |        803        8.03       22.30
      april |        715        7.15       29.45
        may |        987        9.87       39.32
       june |        886        8.86       48.18
       july |        898        8.98       57.16
     august |      1,822       18.22       75.38
  september |        986        9.86       85.24
    october |        974        9.74       94.98
   november |        128        1.28       96.26
   december |        374        3.74      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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