Year	Percent
1961	2.70225
1962	2.8913
1963	2.64691
1964	2.86878
1965	2.51991
1966	2.40803
1967	2.40385
1968	1.99081
1969	2.17552
1970	2.22805
1971	1.91617
1972	2.37557
1973	2.65581
1974	2.86592
1975	3.16602
1976	2.91153
1977	3.12958
1978	3.21396
1979	2.9661
1980	2.0793
1981	1.96076
1982	2.10679
1983	1.98366
1984	1.97261
1985	2.14242
1986	2.02677
1987	2.11679
1988	2.21347
1989	2.11201
1990	1.95649
1993	1.56379
1994	1.43803
1995	1.49702
1996	1.42841
1997	1.49685
1998	1.40463
1999	1.49229
2000	1.64498
2001	1.48727
2002	1.53943
2003	1.58138
2004	1.55392
2005	1.57575
2006	1.56803
2007	1.54473
2008	1.63567
2009	1.61119
2010	1.56153
2011	1.51269
2012	1.4396
2013	1.4058
2014	1.82003
2015	2.36008
2016	2.58312
2017	3.05409