Year	Percent
1986-01-01	50.4892339986949
1987-01-01	50.6921590707624
1988-01-01	51.8972116525459
1989-01-01	52.6185541300455
1990-01-01	52.6711313747556
1991-01-01	52.7081796699730
1992-01-01	53.2307356607581
1993-01-01	55.1674349616215
1994-01-01	55.4284208570916
1995-01-01	54.8266983659223
1996-01-01	54.2184549962094
1997-01-01	54.2045881933795
1998-01-01	54.5163303727821
1999-01-01	54.7722342458487
2000-01-01	54.3833413210403
2001-01-01	53.8583117089400
2002-01-01	53.6910020536187
2003-01-01	54.4464546625236
2004-01-01	55.0347078799772
2005-01-01	55.5503125210799
2006-01-01	54.7678257835547
2007-01-01	54.9397363633706
2008-01-01	56.0409249774494
2009-01-01	55.8676762944664
2010-01-01	58.4660338486802
2011-01-01	59.8000474654800
2012-01-01	59.5465358901919
2013-01-01	59.5503656076816
2014-01-01	59.7982904875540
2015-01-01	59.6634298921799
2016-01-01	59.4617088908765
2017-01-01	59.7028872821507