Year	Percent
1979-01-01	43.4359213437127
1980-01-01	43.5891000720223
1981-01-01	42.5110773676041
1982-01-01	40.8875118916370
1983-01-01	39.0805875806964
1984-01-01	38.9337008184817
1985-01-01	38.1584139085415
1986-01-01	39.3672538283229
1987-01-01	39.3624609281831
1988-01-01	39.7710198052423
1989-01-01	40.8920892353135
1990-01-01	41.5019188391154
1991-01-01	40.1486328223251
1992-01-01	39.3402795842943
1993-01-01	38.5648786413247
1994-01-01	40.2909140860452
1995-01-01	41.6062177597796
1996-01-01	42.2831007683744
1997-01-01	42.7122477059335
1998-01-01	43.6179283830335
1999-01-01	44.0250003754439
2000-01-01	46.0476977827396
2001-01-01	46.7180504581240
2002-01-01	48.4648914036602
2003-01-01	50.2799808985388
2004-01-01	51.6953992194970
2005-01-01	53.4674129533017
2006-01-01	55.4144238701053
2007-01-01	56.5065280777689
2008-01-01	57.3121567036066
2009-01-01	59.0142728077742
2010-01-01	60.6028400498877
2011-01-01	61.1573461047518
2012-01-01	61.4294848985654
2013-01-01	61.3975092647420
2014-01-01	61.4180933585940
2015-01-01	62.1127680466794
2016-01-01	62.4656854178458
2017-01-01	63.5831013266325