Year	Percent change (Units)
1980	9.184
1981	6.002
1982	-8.913
1983	2.120
1984	14.269
1985	-3.554
1986	-1.809
1987	-1.060
1988	-4.351
1989	-23.016
1990	-39.401
1991	-17.909
1992	2.913
1993	11.124
1994	19.037
1995	15.085
1996	-7.046
1997	11.316
1998	-0.607
1999	5.300
2000	23.180
2001	14.260
2002	17.351
2003	8.341
2004	14.144
2005	9.203
2006	11.938
2007	18.857
2008	13.419
2009	-6.149
2010	13.916
2011	11.817
2012	1.166
2013	21.283
2014	8.538
2015	4.545
2016	16.340
2017	7.807
2018	5.228
2019	5.008
2020	-9.314
2021	12.488
2022	9.270
2023	-0.254
2024	4.429
2025	6.922
2026	6.215
2027	5.433
2028	5.266
2029	5.339