Year	Percent
1967	1.42312
1968	1.4732
1969	1.73498
1970	2.29998
1971	3.09762
1972	3.43269
1973	4.17462
1974	5.35513
1975	5.36005
1976	4.68897
1977	5.47665
1978	10.10911
1979	8.5026
1980	4.52063
1981	5.58429
1982	5.4976
1983	5.41432
1984	5.24756
1985	5.38708
1986	5.74462
1987	3.15188
1988	2.44754
1989	2.38264
1990	2.04648
1991	2.18178
1992	2.10604
1993	1.37928
1994	1.29411
1995	1.62721
1996	1.55535
1997	1.54354
1998	1.60197
1999	1.48766
2000	1.48726
2001	1.4516
2002	1.3026
2003	1.07431
2004	0.99461
2005	0.82394
2006	0.79212
2007	0.77304
2008	0.70833
2009	0.76809
2010	0.90892
2011	0.91615
2012	0.92695
2013	1.0001
2014	1.05252
2015	1.13324
2016	1.14214
2017	1.13728