Frequencies for effectivedate variable in nadacc20170705 dataset :

  Effective |
Date of the |
  NADAC Per |
  Unit Cost |      Freq.     Percent        Cum.
------------+-----------------------------------
  29jun2017 |         11       37.93       37.93
  01jul2017 |          1        3.45       41.38
  05jul2017 |         17       58.62      100.00
------------+-----------------------------------
      Total |         29      100.00

by Jean Roth , jroth@nber.org , 10 Feb 2018