Year	Percent change
1980	25.932
1981	27.473
1982	23.276
1983	16.783
1984	18.563
1985	22.727
1986	20.576
1987	24.232
1988	28.297
1989	26.338
1990	32.373
1991	26.889
1992	25.227
1993	22.643
1994	22.602
1995	19.4
1996	21.544
1997	17.541
1998	16.462
1999	9.037
2000	8.511
2001	7.456
2002	6.832
2003	6.375
2004	5.452
2005	4.834
2006	4.459
2007	5.659
2008	7.605
2009	1.92
2010	3.07
2011	3.682
2012	2.455
2013	1.963
2014	3.725
2015	6.82
2016	5.776
2017	4.116
2018	3.175
2019	3.19
2020	3.042
2021	3.042
2022	3.042
2023	3.042
2024	3.042