Year	Percent
1961	1.20346
1962	1.1587
1963	1.32641
1968	1.35015
1969	1.31822
1970	1.61222
1971	1.39159
1972	1.59554
1973	1.62264
1974	1.83665
1975	2.37124
1976	2.36716
1977	2.2475
1978	2.59897
1979	2.70846
1980	3.1724
1981	3.9022
1982	1.98185
1983	1.49932
1984	2.17084
1985	2.01399
1986	2.34555
1987	2.37726
1988	2.02098
1989	2.15629
1990	2.81588
1991	2.68832
1992	2.50612
1993	1.91635
1994	2.2503
1995	2.09616
1996	1.98681
1997	2.27361
1998	2.69111
1999	2.13329
2000	2.06297
2001	2.26491
2002	2.02945
2003	2.14579
2004	1.92498
2005	1.77254
2006	1.56766
2007	1.68658
2008	1.96227
2009	1.9941
2010	1.66624
2011	1.68412
2012	1.84559
2013	1.84091
2014	1.89684
2015	1.74397
2016	1.63442
2017	1.75783