Frequencies for first 10,000 rows of vmonth variable in nhamcsopd2002 dataset :

   month of |
      visit |      Freq.     Percent        Cum.
------------+-----------------------------------
    January |        988        9.88        9.88
   February |        619        6.19       16.07
      March |      1,011       10.11       26.18
      April |        974        9.74       35.92
        May |        690        6.90       42.82
       June |        788        7.88       50.70
       July |        782        7.82       58.52
     August |        850        8.50       67.02
  September |      1,025       10.25       77.27
    October |        661        6.61       83.88
   November |        519        5.19       89.07
   December |      1,093       10.93      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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