Year	Percent
1961	12.96272
1962	16.78635
1963	29.80268
1964	30.32104
1965	4.86049
1966	14.50341
1967	12.91574
1968	13.85028
1969	14.10591
1970	14.87107
1971	11.21845
1972	15.79302
1973	12.71768
1974	30.5673
1975	23.59615
1976	21.29403
1977	14.44432
1978	21.97009
1979	18.53246
1980	24.63007
1981	16.58993
1982	6.4755
1983	4.84773
1984	4.42129
1985	3.99392
1986	4.95587
1987	4.94863
1988	7.10586
1989	6.04188
1990	10.10863
1991	9.48462
1992	7.74293
1993	6.19787
1994	8.10192
1995	6.94095
1996	4.25541
1997	4.06414
1998	4.61694
1999	-1.18452
2000	1.08684
2001	3.65043
2002	3.06049
2003	3.39506
2004	2.9841
2005	1.03157
2006	-0.13984
2007	2.39723
2008	2.95666
2009	3.5423
2010	3.16144
2011	1.5846
2012	1.0435
2013	0.85333
2014	0.60044
2015	2.39466
2016	1.97797
2017	2.26518