Year	Percent change (Units)
1980	0.453
1981	-3.754
1982	-8.303
1983	-6.222
1984	9.378
1985	6.433
1986	6.189
1987	6.660
1988	6.468
1989	4.541
1990	3.595
1991	4.774
1992	4.473
1993	4.772
1994	3.508
1995	4.233
1996	4.765
1997	5.797
1998	5.010
1999	4.529
2000	3.596
2001	3.828
2002	4.617
2003	5.112
2004	5.404
2005	6.230
2006	5.816
2007	4.076
2008	9.008
2009	5.683
2010	7.768
2011	13.949
2012	8.428
2013	7.242
2014	2.856
2015	2.121
2016	3.373
2017	8.129
2018	6.200
2019	6.508
2020	0.514
2021	5.076
2022	3.078
2023	2.259
2024	2.779
2025	4.382
2026	4.945
2027	5.000
2028	5.000
2029	5.000