Frequencies for base variable in hvbp_quarters dataset :

                    Baseline Period |      Freq.     Percent        Cum.
------------------------------------+-----------------------------------
January 1, 2011 - December 31, 2011 |         21       80.77       80.77
    May 1, 2011 - December 31, 2011 |          1        3.85       84.62
    October 1, 2010 - June 30, 2011 |          3       11.54       96.15
   October 15, 2010 - June 30, 2011 |          1        3.85      100.00
------------------------------------+-----------------------------------
                              Total |         26      100.00

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