Year	Percent
1961	1.41177
1962	0.6767
1963	0.5678
1964	2.00839
1965	3.87216
1966	5.26324
1967	3.93666
1968	1.67281
1969	7.3972
1970	3.32292
1971	5.01673
1972	7.80457
1973	9.46631
1974	18.86521
1975	16.23041
1976	16.27414
1977	26.40005
1978	22.34825
1979	19.43742
1980	20.90304
1981	17.60891
1982	20.69033
1983	24.60526
1984	24.67572
1985	21.73456
1986	20.45113
1987	10.09678
1988	11.16539
1989	10.5138
1990	13.14465
1991	10.08619
1992	11.44603
1993	7.37643
1994	7.27763
1995	3.42862
1996	2.38816
1997	3.88656
1998	3.84442
1999	3.39026
2000	3.45961
2001	3.71459
2002	4.20807
2003	3.43904
2004	2.39608
2005	3.32984
2006	3.18539
2007	2.97907
2008	1.73772
2009	1.09632
2010	0.64348
2011	-0.26957
2012	-0.39757
2013	2.26705
2014	0.75028
2015	2.02936
2016	1.51765
2017	1.36882