Year	Percent change (Units)
1981	1.424
1982	-0.446
1983	3.189
1984	7.751
1985	5.137
1986	2.705
1987	3.490
1988	7.522
1989	8.612
1990	5.660
1991	6.605
1992	2.945
1993	3.967
1994	8.670
1995	8.376
1996	4.248
1997	9.754
1998	6.652
1999	9.037
2000	12.304
2001	1.576
2002	0.626
2003	1.822
2004	8.172
2005	5.769
2006	7.160
2007	5.360
2008	1.681
2009	-8.566
2010	9.764
2011	5.157
2012	3.266
2013	2.523
2014	4.621
2015	7.444
2016	1.668
2017	6.489
2018	4.324
2019	1.979
2020	-4.272
2021	8.099
2022	4.496
2023	-1.305
2024	0.200
2025	2.350
2026	3.375
2027	3.375
2028	3.225
2029	3.225