Year	Percent change (Units)
1980	21.847
1981	10.547
1982	11.882
1983	7.434
1984	6.975
1985	3.745
1986	1.864
1987	-0.833
1988	0.553
1989	6.906
1990	3.778
1991	3.831
1992	0.969
1993	4.877
1994	3.670
1995	1.864
1996	2.155
1997	1.642
1998	1.164
1999	1.083
2000	3.448
2001	-0.704
2002	2.286
2003	1.639
2004	2.492
2005	6.199
2006	1.650
2007	7.398
2008	5.172
2009	-2.346
2010	4.215
2011	3.516
2012	1.810
2013	-1.240
2014	-0.628
2015	1.114
2016	0.923
2017	0.531
2018	1.404
2019	0.073
2020	-0.803
2021	1.918
2022	2.905
2023	2.734
2024	1.815
2025	1.977
2026	2.024
2027	2.024
2028	2.024
2029	2.024