Year	Percent change (Units)
1980	6.969
1981	17.467
1982	-3.112
1983	-5.730
1984	19.209
1985	7.702
1986	2.737
1987	-4.571
1988	10.765
1989	6.471
1990	4.415
1991	-3.119
1992	4.301
1993	-2.284
1994	2.615
1995	5.596
1996	2.702
1997	16.609
1998	0.734
1999	1.596
2000	10.939
2001	1.552
2002	-0.635
2003	0.340
2004	10.431
2005	5.053
2006	7.418
2007	10.561
2008	5.421
2009	-10.939
2010	17.190
2011	6.397
2012	-2.300
2013	18.899
2014	-8.498
2015	3.886
2016	6.445
2017	-0.220
2018	2.291
2019	-0.064
2020	-2.688
2021	13.722
2022	6.410
2023	2.873
2024	2.723
2025	3.256
2026	4.000
2027	4.000
2028	4.000
2029	4.050