Year	Percent
1991-01-01	42.0600013732910
1992-01-01	38.2770004272461
1993-01-01	38.5410003662109
1994-01-01	38.4459991455078
1995-01-01	38.3009986877441
1996-01-01	38.7449989318848
1997-01-01	38.5950012207031
1998-01-01	38.6269989013672
1999-01-01	38.4939994812012
2000-01-01	38.3009986877441
2001-01-01	38.6440010070801
2002-01-01	38.5169982910156
2003-01-01	38.4430007934570
2004-01-01	38.4920005798340
2005-01-01	38.5279998779297
2006-01-01	38.5690002441406
2007-01-01	38.5029983520508
2008-01-01	38.4949989318848
2009-01-01	38.4879989624023
2010-01-01	38.5069999694824
2011-01-01	38.5309982299805
2012-01-01	38.5449981689453
2013-01-01	39.7470016479492
2014-01-01	43.2010002136230
2015-01-01	43.1730003356934
2016-01-01	42.9459991455078
2017-01-01	42.6619987487793