Year	Percent
1980	6.05202
1981	5.84832
1982	5.6516
1983	5.44128
1984	6.1175
1985	5.65143
1986	5.62619
1987	5.86223
1988	5.61732
1989	5.16761
1990	5.8883
1991	5.79127
1992	4.67089
1993	3.19945
1994	2.54782
1995	2.05359
1996	1.37903
1997	1.28308
1998	1.23824
1999	1.24921
2000	1.24636
2001	1.30929
2002	1.32003
2003	1.33684
2004	1.38116
2005	1.35
2006	1.56777
2007	1.82077
2008	1.98487
2009	1.51722
2010	1.55859
2011	1.52827
2012	1.48708
2013	1.40898
2014	1.34652
2015	1.1676
2016	1.10335
2017	1.24418