Year	Percent change (Units)
1980	3.181
1981	4.261
1982	3.280
1983	3.630
1984	4.411
1985	5.160
1986	3.294
1987	4.649
1988	6.662
1989	4.926
1990	4.841
1991	3.523
1992	0.901
1993	-0.459
1994	1.083
1995	2.631
1996	3.134
1997	0.981
1998	-1.270
1999	-0.334
2000	2.765
2001	0.386
2002	0.042
2003	1.535
2004	2.186
2005	1.804
2006	1.372
2007	1.484
2008	-1.224
2009	-5.693
2010	4.098
2011	0.024
2012	1.375
2013	2.005
2014	0.296
2015	1.561
2016	0.754
2017	1.675
2018	0.643
2019	-0.402
2020	-4.147
2021	2.559
2022	0.957
2023	1.923
2024	0.855
2025	1.007
2026	0.799
2027	0.594
2028	0.575
2029	0.446