Frequencies for first 10,000 rows of vmonth variable in nhamcsopd2000 dataset :

   month of |
      visit |      Freq.     Percent        Cum.
------------+-----------------------------------
    January |      1,033       10.33       10.33
   February |        748        7.48       17.81
      March |        870        8.70       26.51
      April |        764        7.64       34.15
        May |      1,105       11.05       45.20
       June |      1,041       10.41       55.61
       July |        545        5.45       61.06
     August |        685        6.85       67.91
  September |        690        6.90       74.81
    October |        959        9.59       84.40
   November |        868        8.68       93.08
   December |        692        6.92      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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