Year	Percent change (Units)
1980	-21.600
1981	-5.697
1982	23.171
1983	11.087
1984	-7.140
1985	1.868
1986	-9.785
1987	-0.172
1988	-6.082
1989	6.132
1990	13.595
1991	12.716
1992	3.298
1993	-1.471
1994	-1.698
1995	2.401
1996	6.351
1997	1.350
1998	2.080
1999	2.003
2000	5.846
2001	2.392
2002	8.079
2003	8.639
2004	4.337
2005	3.190
2006	5.000
2007	8.156
2008	0.251
2009	1.007
2010	5.798
2011	2.646
2012	-3.747
2013	-1.522
2014	4.985
2015	-1.425
2016	8.815
2017	2.759
2018	-1.838
2019	-3.071
2020	3.330
2021	4.720
2022	3.777
2023	4.709
2024	3.326
2025	3.050
2026	2.745
2027	2.345
2028	1.993
2029	1.997