Year	Percent
1976-01-01	12.12
1977-01-01	14.04
1978-01-01	15.88
1979-01-01	17.52
1980-01-01	24.25
1981-01-01	31.81
1982-01-01	46.12
1983-01-01	56.44
1984-01-01	47.54
1985-01-01	65.66
1986-01-01	95.33
1987-01-01	104.29
1988-01-01	45.48
1989-01-01	40.11
1990-01-01	29.23
1991-01-01	19.95
1992-01-01	22.76
1993-01-01	14.68
1994-01-01	16.96
1995-01-01	46.54
1996-01-01	26.97
1997-01-01	17.79
1998-01-01	28.56
1999-01-01	15.42
2000-01-01	14.39
2001-01-01	5.81
2002-01-01	5.13
2003-01-01	3.91
2004-01-01	5.84
2005-01-01	5.89
2006-01-01	4.82
2007-01-01	5.13
2008-01-01	6.02
2009-01-01	3.42
2010-01-01	3.28
2011-01-01	3.26
2012-01-01	3.25
2013-01-01	2.64
2014-01-01	2.15
2015-01-01	2.11
2016-01-01	3.28
2017-01-01	4.62