Frequencies for first 10,000 rows of vmonth variable in nhamcsed1998 dataset :

   month of |
      visit |      Freq.     Percent        Cum.
------------+-----------------------------------
    January |        730        7.30        7.30
   February |        656        6.56       13.86
      March |        864        8.64       22.50
      April |        860        8.60       31.10
        May |        894        8.94       40.04
       June |        998        9.98       50.02
       July |        952        9.52       59.54
     August |        707        7.07       66.61
  September |      1,034       10.34       76.95
    October |        957        9.57       86.52
   November |        673        6.73       93.25
   December |        675        6.75      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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