Year	Percent change (Units)
1981	-4.000
1982	4.100
1983	2.000
1984	4.900
1985	5.800
1986	-2.100
1987	-15.400
1988	3.500
1989	15.431
1990	5.147
1991	6.124
1992	-3.087
1993	3.947
1994	3.713
1995	4.974
1996	3.625
1997	5.738
1998	3.478
1999	-8.943
2000	-1.883
2001	2.150
2002	0.187
2003	1.701
2004	1.120
2005	-0.786
2006	-1.908
2007	6.333
2008	1.733
2009	-2.279
2010	6.270
2011	7.092
2012	5.251
2013	5.517
2014	4.435
2015	3.879
2016	2.091
2017	0.473
2018	0.909
2019	3.823
2020	-1.815
2021	1.468
2022	3.037
2023	2.266
2024	2.902
2025	2.671
2026	2.608
2027	2.593
2028	2.585
2029	2.629