Year	Percent change (Units)
1980	12.148
1981	22.489
1982	-0.943
1983	-3.925
1984	6.332
1985	-15.932
1986	0.811
1987	-5.256
1988	19.320
1989	16.369
1990	8.869
1991	-7.386
1992	13.124
1993	5.710
1994	-0.133
1995	6.291
1996	-2.487
1997	8.702
1998	5.345
1999	5.821
2000	6.549
2001	15.059
2002	-3.011
2003	-2.125
2004	7.806
2005	-1.747
2006	5.659
2007	8.605
2008	4.778
2009	-4.592
2010	15.426
2011	-3.816
2012	8.426
2013	-1.505
2014	2.974
2015	-2.569
2016	5.210
2017	3.368
2018	1.004
2019	-8.565
2020	-15.042
2021	9.547
2022	12.145
2023	5.522
2024	6.000
2025	5.600
2026	5.000
2027	1.500
2028	0.500
2029	1.500