Year	Percent change (Units)
1981	-5.104
1982	9.004
1983	6.549
1984	42.477
1985	18.659
1986	-13.555
1987	-6.968
1988	-4.979
1989	0.127
1990	-3.686
1991	-3.083
1992	-15.751
1993	10.103
1994	6.077
1995	32.728
1996	-12.098
1997	11.859
1998	2.771
1999	8.110
2000	3.110
2001	80.288
2002	163.557
2003	-31.945
2004	50.816
2005	31.653
2006	35.613
2007	-18.357
2008	10.132
2009	-1.322
2010	12.650
2011	5.690
2012	0.287
2013	-3.988
2014	14.016
2015	-19.878
2016	2.303
2017	16.476
2018	12.319
2019	-4.523
2020	-10.167
2021	10.080
2022	-12.748
2023	21.224
2024	-2.073
2025	1.029
2026	-0.707
2027	-2.353
2028	0.098
2029	0.030