Year	Percent change (Units)
1980	10.004
1981	15.332
1982	4.715
1983	3.000
1984	6.438
1985	9.122
1986	4.829
1987	-0.960
1988	-2.100
1989	9.893
1990	6.686
1991	3.999
1992	6.999
1993	5.867
1994	8.160
1995	7.045
1996	6.892
1997	6.907
1998	4.279
1999	4.028
2000	6.429
2001	4.772
2002	6.809
2003	6.179
2004	7.187
2005	6.940
2006	8.954
2007	7.851
2008	7.822
2009	7.373
2010	8.018
2011	7.986
2012	7.805
2013	8.026
2014	7.612
2015	7.270
2016	7.023
2017	6.851
2018	6.289
2019	4.652
2020	-0.435
2021	2.061
2022	2.252
2023	3.697
2024	3.969
2025	3.973
2026	4.075
2027	4.236
2028	4.435
2029	4.597