Year	Percent
1960	1.81608
1961	1.87653
1962	1.935
1963	1.99252
1964	2.04942
1965	2.10537
1966	2.12959
1967	2.14673
1968	2.20933
1969	2.33092
1970	2.47227
1971	2.588
1972	2.62866
1973	2.57602
1974	2.41266
1975	2.15765
1976	1.9663
1977	1.75426
1978	1.29402
1979	0.51959
1980	-0.43928
1981	-1.47834
1982	-2.35876
1983	-2.86727
1984	-2.80055
1985	-2.21632
1986	-1.55672
1987	-0.85077
1988	0.33091
1989	2.0304
1990	3.92534
1991	5.90077
1992	7.32545
1993	7.66543
1994	6.89557
1995	5.57258
1996	4.14316
1997	3.08672
1998	2.59049
1999	2.82072
2000	3.49466
2001	4.2515
2002	4.72053
2003	4.81804
2004	4.46892
2005	3.87047
2006	3.22863
2007	2.75523
2008	2.51257
2009	2.56911
2010	2.81262
2011	3.09512
2012	3.2727
2013	3.31522
2014	3.1832
2015	2.94323
2016	2.68916
2017	2.49079