Year	Percent
1973	1.64596
1974	2.85057
1975	6.95811
1976	8.3526
1977	6.07458
1978	3.89085
1979	3.71501
1980	3.70027
1981	3.9449
1982	5.12656
1983	4.51635
1984	4.67471
1985	8.43686
1986	5.35586
1987	3.08609
1988	2.66377
1989	1.58374
1990	0.90583
1991	0.58289
1992	0.96969
1993	0.95095
1994	1.00594
1995	0.91552
1996	0.78783
2000	1.76598
2001	2.01795
2002	2.29329
2003	2.19972
2004	2.80932
2005	2.24354
2006	1.31489
2007	1.43489
2008	1.58747
2009	1.53319
2010	1.37544
2011	1.25812
2012	1.17646
2013	1.17603
2014	1.27656
2015	1.34269
2016	1.36865
2017	1.44368