Year	Percent
1981	1.4424
1982	1.41831
1983	1.29995
1984	1.1127
1985	1.20329
1986	1.1197
1987	1.42137
1988	1.43176
1989	2.0606
1990	2.20632
1991	3.52932
1992	3.52285
1993	3.3735
1994	3.1649
1995	3.08017
1996	3.5862
1997	3.7374
1998	4.15222
1999	4.9109
2000	7.91159
2001	7.62298
2002	6.29769
2003	7.61857
2004	5.03898
2005	5.95884
2006	7.48456
2007	9.95659
2008	10.63737
2009	7.56422
2010	6.93616
2011	7.49178
2012	6.95616
2013	5.54198
2014	3.49777
2015	6.4064
2016	4.20323