Year	Percent
1960	3.37305
1961	3.46518
1962	3.61227
1963	3.62625
1964	3.54152
1965	3.37961
1966	3.22965
1967	3.72752
1968	3.71457
1969	3.4329
1970	3.14067
1971	2.82509
1972	1.96875
1973	1.44509
1974	1.27182
1975	1.1552
1976	1.04552
1977	0.75076
1978	0.58859
1979	0.58209
1980	0.60909
1981	0.65368
1982	0.65243
1983	0.6214
1984	0.56723
1985	0.46975
1986	0.35014
1987	0.26107
1988	0.25162
1989	0.35878
1990	0.53433
1991	0.73869
1992	1.18033
1993	1.40218
1994	1.35515
1995	1.22789
1996	1.07804
1997	0.94354
1998	0.87109
1999	0.85831
2000	0.90574
2001	0.95958
2002	0
2003	-0.50457
2004	-0.48888
2005	-0.48081
2006	-0.47787
2007	-0.45108
2008	-0.41594
2009	-0.39103
2010	-0.35778
2011	-0.32418
2012	-0.37101
2013	-0.40213
2014	-0.42276
2015	-0.47366
2016	-0.539
2017	-0.56123