Year	Percent change (Units)
1980	0.679
1981	-1.556
1982	-1.130
1983	-1.078
1984	2.007
1985	2.513
1986	0.515
1987	-2.257
1988	4.288
1989	3.799
1991	3.102
1992	0.697
1993	-1.599
1994	2.000
1995	2.100
1996	2.862
1997	4.484
1998	3.895
1999	3.073
2000	3.920
2001	4.132
2002	3.923
2003	5.795
2004	5.061
2005	0.599
2006	5.652
2007	3.274
2008	-0.335
2009	-4.301
2010	-5.478
2011	-10.149
2012	-7.087
2013	-2.516
2014	0.476
2015	-0.196
2016	-0.487
2017	1.092
2018	1.668
2019	1.880
2020	-9.316
2021	8.380
2022	5.557
2023	2.011
2024	2.038
2025	1.932
2026	1.706
2027	1.326
2028	1.315
2029	1.254