Year	Percent
1986-01-01	68.4943202482612
1987-01-01	67.4435988857623
1988-01-01	62.1979280690032
1989-01-01	58.3127812139408
1990-01-01	58.5805248801024
1991-01-01	54.3551339223010
1992-01-01	52.9660973548918
1993-01-01	53.1351768692970
1994-01-01	55.8101603118165
1995-01-01	58.8610066399751
1996-01-01	58.7866555029068
1997-01-01	57.6394820161140
1998-01-01	55.1874197782058
1999-01-01	54.0112450797792
2000-01-01	54.2011389073270
2001-01-01	55.3397312972801
2002-01-01	56.1598492589777
2003-01-01	55.8691646608164
2004-01-01	56.1777019174320
2005-01-01	56.2613113367524
2006-01-01	58.0129772985254
2007-01-01	57.9998491709110
2008-01-01	55.8208484507310
2009-01-01	51.0842451231601
2010-01-01	49.3997856943084
2011-01-01	49.1890594914382
2012-01-01	48.6113169720678
2013-01-01	49.2007913260373
2014-01-01	51.7115119692433
2015-01-01	53.0713275646322
2016-01-01	54.2902272947003
2017-01-01	55.3860453620351