Year	Percent change (Units)
1980	19.332
1981	8.559
1982	5.975
1983	2.230
1984	2.727
1985	2.666
1986	-0.029
1987	0.937
1988	0.230
1989	5.133
1990	4.200
1991	4.201
1992	2.837
1993	1.791
1994	1.427
1995	3.000
1996	2.048
1997	8.675
1998	3.684
1999	3.351
2000	2.110
2001	2.138
2002	2.078
2003	2.268
2004	2.250
2005	3.374
2006	8.487
2007	4.481
2008	5.300
2009	2.058
2010	0.851
2011	5.835
2012	0.816
2013	1.107
2014	0.248
2015	-2.302
2016	-0.688
2017	0.696
2018	-1.036
2019	-0.331
2020	-1.177
2021	1.206
2022	2.669
2023	3.611
2024	2.460
2025	2.223
2026	2.044
2027	2.044
2028	2.044
2029	2.044