Year	Percent
1986-01-01	31.7167046794716
1987-01-01	32.3322441782563
1988-01-01	35.3123031941955
1989-01-01	38.2513865848378
1990-01-01	35.4691911799476
1991-01-01	36.5415540227384
1992-01-01	38.4922794247179
1993-01-01	39.3520895816082
1994-01-01	37.9579060147604
1995-01-01	37.0070311318062
1996-01-01	36.6293035177758
1997-01-01	36.2684282761547
1998-01-01	38.0116905622581
1999-01-01	40.7875558386947
2000-01-01	40.4805072674302
2001-01-01	40.2881794488204
2002-01-01	39.4912185695465
2003-01-01	40.4973651938065
2004-01-01	41.3522363117911
2005-01-01	40.8568630767742
2006-01-01	38.5126255812939
2007-01-01	38.2411564829108
2008-01-01	40.1257311812989
2009-01-01	41.9064755641526
2010-01-01	42.7332878445774
2011-01-01	43.9391676265631
2012-01-01	43.7568806004393
2013-01-01	43.9032222847292
2014-01-01	42.1971154049420
2015-01-01	40.8368203692764
2016-01-01	40.0145907949950
2017-01-01	38.6994027156657