Year	Percent change (Units)
1980	18.999
1981	11.465
1982	4.170
1983	2.346
1984	3.844
1985	0.996
1986	0.500
1987	3.602
1988	6.800
1989	4.362
1990	6.591
1991	4.518
1992	3.000
1993	3.100
1994	6.485
1995	2.737
1996	2.965
1997	0.362
1998	3.262
1999	1.135
2000	-0.162
2001	1.935
2002	2.408
2003	1.994
2004	2.030
2005	2.099
2006	1.788
2007	1.416
2008	5.334
2009	-0.550
2010	3.370
2011	3.457
2012	3.377
2013	1.059
2014	1.089
2015	0.969
2016	-0.489
2017	2.432
2018	1.211
2019	1.431
2020	1.058
2021	1.627
2022	7.531
2023	5.067
2024	2.634
2025	2.046
2026	1.997
2027	1.997
2028	1.997
2029	1.997