Year	Percent
1961	6.12346
1962	5.69071
1963	6.84714
1964	6.02235
1965	6.69562
1966	6.12558
1967	5.2018
1968	5.0232
1969	5.31043
1970	5.60195
1971	5.65123
1972	5.45164
1973	5.11395
1974	4.02109
1975	3.77497
1976	3.79371
1977	4.03977
1978	3.92138
1979	3.55758
1980	3.42213
1981	3.45682
1982	3.21826
1983	3.07037
1984	2.92367
1985	2.97826
1986	2.87914
1987	1.9724
1988	2.14085
1989	2.95911
1990	3.39589
1991	3.171
1992	3.35452
1993	3.52311
1994	3.54112
1995	3.68483
1996	3.49343
1997	2.66539
1998	2.31424
1999	1.99454
2000	2.30537
2001	1.80006
2002	1.29888
2003	1.92436
2004	1.90911
2005	1.56049
2012	3.71104
2013	3.80915
2014	3.57903
2015	4.07723
2016	3.73747
2017	2.4833