Year	Percent
1960	3.49153
1961	3.14407
1962	3.0139
1963	2.72552
1964	2.55558
1965	2.25344
1966	2.01677
1967	1.70125
1968	1.61245
1969	1.60171
1970	1.7809
1971	1.99313
1972	2.15032
1973	2.09134
1974	1.71223
1975	1.13874
1976	0.51817
1977	-0.03976
1978	-0.13266
1979	0.21217
1980	1.01484
1981	2.94595
1982	3.79761
1983	4.25954
1984	4.22072
1985	3.84408
1986	3.28318
1987	2.32183
1988	2.24911
1989	2.33674
1990	2.72244
1991	3.06678
1992	3.1994
1993	3.29947
1994	3.31974
1995	3.13195
1996	2.3338
1997	2.07115
1998	1.85397
1999	1.55042
2000	1.20843
2001	0.84171
2002	0.52066
2003	0.28485
2004	1.64922
2005	1.60129
2006	1.58995
2007	1.54454
2008	1.56147
2009	1.53746
2010	1.5795
2011	1.55494
2012	1.664
2013	1.65542
2014	1.67128
2015	1.74002
2016	1.79294
2017	1.79036