Year	Percent
1960	15.48415
1961	6.63898
1962	3.04714
1963	1.7884
1964	1.78785
1965	4.54178
1966	4.187
1967	2.52433
1968	3.57565
1969	10.2416
1970	4.53417
1971	1.49057
1972	-1.30318
1973	5.70621
1974	0.29936
1975	0.51222
1976	10.54993
1977	7.59563
1978	5.54269
1979	8.86051
1980	2.46111
1981	-6.25615
1982	-8.79328
1983	-5.74379
1984	1.86743
1985	5.10396
1986	6.06979
1987	13.8694
1988	10.20678
1989	6.06463
1990	2.04399
1991	-3.66037
1992	1.35651
1993	-0.09989
1994	-1.6034
1995	-3.93488
1996	1.38611
1997	0.91414
1998	21.99517
1999	25.0517
2000	19.21263
2001	17.44035
2002	17.25468
2003	19.69152
2004	20.37237
2005	21.94349
2006	21.79368
2007	19.87104
2008	22.33094
2009	20.27456
2010	15.91583
2011	15.5732
2012	10.75807
2013	8.53709
2014	9.27477
2015	7.65226
2016	6.68975
2017	7.02703