Year	Percent change (Units)
1980	21.058
1981	22.227
1982	-7.915
1983	-15.436
1984	20.059
1985	30.465
1986	10.753
1987	30.479
1988	-20.393
1989	7.582
1990	-4.100
1991	6.400
1992	7.700
1993	2.300
1994	7.066
1995	8.700
1996	-2.691
1997	6.799
1998	2.818
1999	2.891
2000	7.859
2001	20.607
2002	21.985
2003	11.427
2004	11.137
2005	-1.616
2006	15.244
2007	-2.796
2008	2.203
2009	-14.950
2010	12.015
2011	2.951
2012	-7.658
2013	7.479
2014	3.657
2015	-1.834
2016	5.213
2017	-2.257
2018	-3.534
2019	17.659
2020	-3.198
2021	7.316
2022	7.555
2023	1.483
2024	3.419
2025	3.196
2026	3.208
2027	3.248
2028	3.239
2029	3.212