Frequencies for first 10,000 rows of vmonth variable in nhamcsopd2003 dataset :

   month of |
      visit |      Freq.     Percent        Cum.
------------+-----------------------------------
    january |        620        6.20        6.20
   february |        269        2.69        8.89
      march |        903        9.03       17.92
      april |        687        6.87       24.79
        may |        661        6.61       31.40
       june |        780        7.80       39.20
       july |        821        8.21       47.41
     august |      1,234       12.34       59.75
  september |      1,524       15.24       74.99
    october |        499        4.99       79.98
   november |        896        8.96       88.94
   december |      1,106       11.06      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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