Year	Percent change (Units)
1980	11.887
1981	8.569
1982	4.017
1983	3.930
1984	3.896
1985	3.309
1986	1.693
1987	4.184
1988	4.491
1989	4.932
1990	5.763
1991	2.929
1992	3.148
1993	2.654
1994	2.722
1995	2.705
1996	3.088
1997	1.686
1998	1.607
1999	2.939
2000	3.427
2001	1.552
2002	2.616
2003	1.909
2004	3.209
2005	3.683
2006	2.199
2007	4.084
2008	0.701
2009	1.919
2010	1.689
2011	3.086
2012	1.822
2013	1.319
2014	0.524
2015	0.695
2016	2.197
2017	2.178
2018	1.921
2019	2.086
2020	1.561
2021	7.392
2022	6.413
2023	3.201
2024	2.390
2025	1.964
2026	2.101
2027	2.371
2028	2.135
2029	2.152