Year	Percent
1978-01-01	5.2226300000000005
1979-01-01	6.6604600000000005
1980-01-01	10.3676000000000000
1981-01-01	12.0053000000000000
1982-01-01	12.3849000000000000
1983-01-01	10.7836000000000000
1984-01-01	11.4048000000000000
1985-01-01	15.9612000000000000
1986-01-01	19.7088000000000000
1987-01-01	17.0644000000000000
1988-01-01	17.6155000000000000
1989-01-01	21.7119000000000000
1990-01-01	17.2065000000000000
1991-01-01	14.3392000000000000
1992-01-01	10.5853000000000000
1993-01-01	9.2112699999999990
1994-01-01	8.7628500000000000
1995-01-01	8.5582600000000000
1996-01-01	8.3239500000000000
1997-01-01	8.1141800000000010
1998-01-01	8.7011700000000000
1999-01-01	9.3958900000000000
2000-01-01	10.9932000000000000
2001-01-01	9.7314100000000000
2002-01-01	8.3844800000000000
2003-01-01	9.1359700000000000
2004-01-01	9.2788000000000000
2005-01-01	10.4389000000000000
2006-01-01	15.2305000000000000
2007-01-01	20.9222000000000000
2008-01-01	24.7438000000000000
2009-01-01	26.0410000000000000
2010-01-01	21.7471000000000000
2011-01-01	17.1282000000000000
2012-01-01	16.0709999999999980
2013-01-01	16.9680000000000000
2014-01-01	19.0794000000000000
2015-01-01	20.1560000000000000
2016-01-01	21.5349000000000000