Year	Percent
1960	2.51085
1961	2.11384
1962	1.80295
1963	1.70208
1964	1.87571
1965	2.22726
1966	2.62982
1967	2.94601
1968	3.13739
1969	3.16238
1970	3.082
1971	2.98587
1972	2.93863
1973	2.93419
1974	2.98921
1975	3.08188
1976	3.17045
1977	3.23859
1978	3.30375
1979	3.36406
1980	3.41601
1981	3.33467
1982	3.22657
1983	3.30216
1984	3.60546
1985	3.96987
1986	4.59164
1987	4.93957
1988	4.33204
1989	2.60925
1990	0.2736
1991	-2.57636
1992	-5.08933
1993	-6.18486
1994	-4.79269
1995	-1.29082
1996	3.10722
1997	6.44674
1998	7.91789
1999	7.28397
2000	5.5391
2001	3.71429
2002	2.45244
2003	1.67449
2004	1.57834
2005	1.94611
2006	2.36126
2007	2.58213
2008	2.72279
2009	2.73594
2010	2.66424
2011	2.59351
2012	2.56088
2013	2.52871
2014	2.5008
2015	2.47409
2016	2.4459
2017	2.41162