Year	Percent
1960	4.56993
1961	4.16917
1962	3.89106
1963	3.74764
1964	3.95106
1965	4.26021
1966	4.6901
1967	4.99857
1968	5.21375
1969	5.19616
1970	5.13811
1971	7.33596
1972	7.48002
1973	7.443
1974	7.51277
1975	7.6098
1976	7.67002
1977	7.72783
1978	7.79628
1979	5.11945
1980	4.80212
1981	4.70201
1982	4.61703
1983	4.67329
1984	4.97788
1985	5.34393
1986	5.96621
1987	6.31495
1988	5.70762
1989	3.96629
1990	1.64944
1991	-1.20114
1992	8.46386
1993	8.91621
1994	10.13101
1995	13.43526
1996	17.62512
1997	15.61424
1998	13.97192
1999	13.29129
2000	11.48771
2001	9.58825
2002	8.26893
2003	2.42865
2004	1.60194
2005	1.96978
2006	2.39083
2007	2.60579
2008	2.74645
2009	2.76548
2010	2.68783
2011	2.61714
2012	2.59038
2013	2.55233
2014	2.61876
2015	2.6919
2016	2.75125
2017	2.81538