Year	Percent change (Units)
1980	12.678
1981	2.613
1982	2.410
1983	2.393
1984	2.375
1985	2.359
1986	2.343
1987	2.327
1988	21.908
1989	21.269
1990	1.003
1991	3.402
1992	4.181
1993	1.316
1994	-1.401
1995	3.965
1996	3.495
1997	-1.004
1998	8.950
1999	-3.678
2000	11.752
2001	-4.823
2002	0.985
2003	0.459
2004	-0.197
2005	9.211
2006	7.986
2007	-6.614
2008	6.306
2009	11.637
2010	9.931
2011	2.206
2012	9.947
2013	-0.712
2014	6.717
2015	-3.551
2016	-4.994
2017	-5.595
2018	-2.304
2019	1.124
2020	-6.268
2021	1.057
2022	1.750
2023	4.033
2024	4.432
2025	3.234
2026	3.748
2027	3.879
2028	3.949
2029	4.013