Year	Percent change
1980	58.548
1981	50.864
1982	51.019
1983	84.275
1984	29.17
1985	32.376
1986	21.273
1987	18.763
1988	25.456
1989	14.509
1990	15.51
1991	6.808
1992	3.959
1993	4.083
1994	1.552
1995	1.654
1996	2.254
1997	1.791
1998	1.704
1999	3.222
2000	5.119
2001	6.395
2002	5.174
2003	2.065
2004	3.151
2005	4
2006	6.676
2007	5.064
2008	12.678
2009	12.003
2010	5.396
2011	4.001
2012	5.186
2013	3.872
2014	2.044
2015	1.633
2016	1.697
2017	1.761
2018	2.683
2019	2.791
2020	2.541
2021	2.5
2022	2.5
2023	2.5
2024	2.5