Frequencies for msr_strt_dttime variable in vwmeasure_dates dataset :

msr_strt_dt |
       time |      Freq.     Percent        Cum.
------------+-----------------------------------
   1/1/2009 |          4        5.71        5.71
   1/1/2011 |          2        2.86        8.57
  10/1/2008 |         18       25.71       34.29
  10/1/2010 |          3        4.29       38.57
   4/1/2010 |         37       52.86       91.43
   7/1/2007 |          6        8.57      100.00
------------+-----------------------------------
      Total |         70      100.00

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