Year	Percent
1978	-0.82176
1979	0.84392
1980	1.33592
1981	0.48978
1982	1.31857
1983	1.71772
1984	1.03685
1985	1.23591
1986	4.58223
1987	2.8266
1988	4.53906
1989	4.93264
1990	3.18959
1991	3.49108
1992	5.00083
1993	10.96722
1994	16.20891
1995	9.69618
1996	12.86449
1997	26.58952
1998	23.80812
1999	14.53635
2000	9.52493
2001	4.89265
2002	7.37161
2003	11.44951
2004	12.58416
2005	7.27896
2006	17.86004
2007	18.31862
2008	22.89858
2009	16.33101
2010	14.27105
2011	12.66383
2012	16.65415
2013	17.57262
2014	16.06431
2015	7.19988
2016	11.94074
2017	11.02522