2008-03-31   21.070
2008-04-29   21.300
2009-11-06   20.950
2010-02-11   21.370
2010-04-01   21.190
2010-05-31   21.060
2010-12-08   20.650
2012-01-16   21.260
2012-04-20   21.060
2013-01-03   20.510
2013-03-13   21.000
2013-06-16   21.070
2015-01-14   21.100
2015-11-30   20.830
2017-02-10   21.570