Frequencies for msr_strt_dttime variable in vwmeasure_dates dataset :

msr_strt_dt |
       time |      Freq.     Percent        Cum.
------------+-----------------------------------
   1/1/2010 |          6        7.23        7.23
   1/1/2011 |          6        7.23       14.46
   1/1/2012 |         11       13.25       27.71
  10/1/2010 |          1        1.20       28.92
   4/1/2011 |         35       42.17       71.08
   7/1/2008 |          6        7.23       78.31
   7/1/2009 |         18       21.69      100.00
------------+-----------------------------------
      Total |         83      100.00

by Jean Roth , jroth@nber.org , 16 Nov 2016