Year	Percent
1978-01-01	49.2633969247563
1979-01-01	49.6240241455152
1980-01-01	49.6986846250375
1981-01-01	49.7993323994301
1982-01-01	50.2843238848920
1983-01-01	51.4114536950829
1984-01-01	51.3915270282766
1985-01-01	51.3453536546721
1986-01-01	51.3892998886859
1987-01-01	51.5549199445978
1988-01-01	51.9159461541565
1989-01-01	52.6905276880717
1990-01-01	53.4614003981850
1991-01-01	54.1960903862276
1992-01-01	54.4265965657350
1993-01-01	54.1169999396981
1994-01-01	54.0837515104708
1995-01-01	54.0294052472068
1996-01-01	54.2550841597597
1997-01-01	54.8126485267042
1998-01-01	54.7501931810789
1999-01-01	54.4017703338884
2000-01-01	54.2630167357670
2001-01-01	54.4123775423020
2002-01-01	53.9959207414376
2003-01-01	53.9983009386876
2004-01-01	54.1894115458126
2005-01-01	54.6226746442581
2006-01-01	55.0340789184555
2007-01-01	55.3692501738173
2008-01-01	55.6051378777211
2009-01-01	56.0857956533271
2010-01-01	56.3181895230626
2011-01-01	56.3016420157666
2012-01-01	56.5239850716074
2013-01-01	57.7145769188430
2014-01-01	58.3907204905805
2015-01-01	59.0184279581210
2016-01-01	60.1930708021698
2017-01-01	61.4426287812769