Year	Percent
1974	2.16501
1975	1.76972
1976	1.16453
1977	1.40465
1978	1.5766
1979	2.39758
1980	3.91059
1981	4.11529
1982	5.31802
1983	5.63047
1984	6.28216
1985	9.6851
1986	9.08759
1987	8.79926
1988	5.7624
1989	4.36216
1990	5.39476
1991	3.03269
1992	2.31884
1993	2.26778
1994	2.22772
1995	1.53871
1996	2.60487
1997	2.32215
1998	2.23016
1999	3.03697
2000	2.15037
2001	2.22154
2002	1.55594
2003	1.46973
2004	2.15101
2005	1.7912
2006	1.81463
2007	2.08029
2008	2.7542
2009	2.24725
2010	2.00928
2011	1.88777
2012	2.19124
2013	1.3818
2014	1.70071
2015	1.32955
2016	2.09053