Year	Percent
1991-01-01	33.4939994812012
1992-01-01	33.5820007324219
1993-01-01	33.7150001525879
1994-01-01	33.5950012207031
1995-01-01	33.6209983825684
1996-01-01	30.0319995880127
1997-01-01	31.3579998016357
1998-01-01	33.5040016174316
1999-01-01	34.5639991760254
2000-01-01	33.8380012512207
2001-01-01	29.1909999847412
2002-01-01	26.3810005187988
2003-01-01	29.3579998016357
2004-01-01	29.6389999389648
2005-01-01	31.2159996032715
2006-01-01	31.3780002593994
2007-01-01	32.9309997558594
2008-01-01	31.5240001678467
2009-01-01	31.3050003051758
2010-01-01	31.1720008850098
2011-01-01	33.6489982604980
2012-01-01	33.2659988403320
2013-01-01	33.0999984741211
2014-01-01	32.3540000915527
2015-01-01	33.6790008544922
2016-01-01	33.3120002746582
2017-01-01	33.3079986572266