Year	Percent
1973-01-01	4.2188099999999995
1974-01-01	6.0398100000000000
1975-01-01	7.3847200000000000
1976-01-01	7.8176900000000000
1977-01-01	9.3917500000000000
1978-01-01	10.4564000000000000
1979-01-01	10.8514000000000000
1980-01-01	10.3179000000000000
1981-01-01	10.2509000000000000
1982-01-01	10.5130000000000000
1983-01-01	10.3643000000000000
1984-01-01	9.6756600000000000
1985-01-01	8.8981000000000000
1986-01-01	8.0934100000000000
1987-01-01	15.3197000000000000
1988-01-01	26.5963000000000000
1989-01-01	35.0463000000000000
1990-01-01	33.6137000000000000
1991-01-01	33.2190000000000000
1992-01-01	38.2482000000000000
1993-01-01	29.6787000000000000
1994-01-01	11.9457000000000000
1995-01-01	10.3487000000000000
1996-01-01	11.2545000000000000
1997-01-01	13.8630000000000000
1998-01-01	14.7763000000000000
1999-01-01	14.5218000000000000
2000-01-01	15.5554000000000000
2001-01-01	15.9884000000000000
2002-01-01	16.5708000000000000
2003-01-01	18.7707000000000000
2004-01-01	17.3865000000000000
2005-01-01	16.2582000000000000
2006-01-01	15.3254000000000000
2007-01-01	13.2354000000000000
2008-01-01	13.7239000000000000
2009-01-01	14.1957000000000000
2010-01-01	15.8163000000000000
2011-01-01	15.3641000000000000
2012-01-01	17.1044000000000000
2013-01-01	18.8233000000000000
2014-01-01	19.7517000000000000
2015-01-01	19.9627000000000000
2016-01-01	19.3695000000000000