Year	Percent change (Units)
1980	11.712
1981	9.170
1982	-1.398
1983	-3.043
1984	2.817
1985	3.872
1986	0.263
1987	4.072
1988	5.881
1989	5.817
1990	4.120
1991	3.490
1992	1.696
1993	4.936
1994	5.318
1995	6.823
1996	1.574
1997	4.243
1998	0.068
1999	-1.366
2000	-2.314
2001	-0.834
2002	-0.021
2003	4.321
2004	4.057
2005	2.133
2006	4.807
2007	5.422
2008	6.496
2009	-0.261
2010	11.095
2011	4.286
2012	-0.708
2013	8.293
2014	5.301
2015	2.957
2016	4.268
2017	4.810
2018	3.204
2019	-0.402
2020	-0.820
2021	4.017
2022	0.176
2023	4.477
2024	3.800
2025	3.800
2026	3.500
2027	3.500
2028	3.500
2029	3.500