Year	Percent change (Units)
1980	18.724
1981	13.269
1982	-33.994
1983	-17.671
1984	12.002
1985	-9.462
1986	7.904
1987	18.610
1988	12.793
1989	25.038
1990	5.800
1991	7.129
1992	21.812
1993	13.970
1994	10.150
1995	25.158
1996	11.867
1997	14.597
1998	6.877
1999	-9.894
2000	10.569
2001	4.997
2002	1.838
2003	7.873
2004	19.506
2005	18.370
2006	12.536
2007	13.754
2008	10.858
2009	-17.701
2010	25.243
2011	15.839
2012	3.816
2013	1.764
2014	-6.485
2015	-1.177
2016	1.387
2017	5.070
2018	8.300
2019	-1.918
2020	-12.579
2021	31.626
2022	2.027
2023	-11.694
2024	4.148
2025	4.498
2026	3.009
2027	2.609
2028	2.596
2029	2.545