Year	Percent change (Units)
1980	0.599
1981	-1.222
1982	-2.075
1983	0.906
1984	6.327
1985	5.626
1986	5.331
1987	6.638
1988	1.746
1989	2.728
1990	2.792
1991	-3.319
1992	6.074
1993	6.496
1994	0.212
1995	6.189
1996	1.871
1997	4.598
1998	3.590
1999	-0.736
2000	7.291
2001	2.723
2002	3.754
2003	4.547
2004	6.232
2005	6.051
2006	6.567
2007	6.188
2008	4.232
2009	-2.432
2010	3.731
2011	3.836
2012	4.129
2013	2.792
2014	3.058
2015	3.840
2016	3.893
2017	4.843
2018	3.845
2019	2.653
2020	-8.965
2021	12.534
2022	3.998
2023	3.500
2024	3.600
2025	3.740
2026	3.800
2027	3.940
2028	3.900
2029	3.940