Frequencies for first 10,000 rows of vmonth variable in namcs1999 dataset :

   month of |
      visit |      Freq.     Percent        Cum.
------------+-----------------------------------
    January |      1,008       10.08       10.08
   February |        750        7.50       17.58
      March |        858        8.58       26.16
      April |        885        8.85       35.01
        May |        734        7.34       42.35
       June |        671        6.71       49.06
       July |        695        6.95       56.01
     August |        732        7.32       63.33
  September |      1,001       10.01       73.34
    October |        720        7.20       80.54
   November |      1,117       11.17       91.71
   December |        829        8.29      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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