Year	Percent
1991-01-01	37.9910011291504
1992-01-01	38.3120002746582
1993-01-01	38.5169982910156
1994-01-01	38.2270011901855
1995-01-01	38.1440010070801
1996-01-01	38.7430000305176
1997-01-01	38.6230010986328
1998-01-01	38.5849990844727
1999-01-01	38.3750000000000
2000-01-01	37.9710006713867
2001-01-01	37.8230018615723
2002-01-01	37.6860008239746
2003-01-01	37.9550018310547
2004-01-01	37.8030014038086
2005-01-01	38.9659996032715
2006-01-01	40.3680000305176
2007-01-01	41.6259994506836
2008-01-01	42.9609985351563
2009-01-01	42.9830017089844
2010-01-01	42.9389991760254
2011-01-01	42.8650016784668
2012-01-01	42.5559997558594
2013-01-01	42.4519996643066
2014-01-01	42.6590003967285
2015-01-01	42.8190002441406
2016-01-01	42.6069984436035
2017-01-01	42.6780014038086