Year	Percent change (Units)
1980	-39.000
1981	17.300
1982	1.700
1983	-2.700
1984	2.200
1985	-9.400
1986	-6.500
1987	-1.500
1988	26.900
1989	-22.000
1990	-15.800
1991	-3.886
1992	21.141
1993	-19.125
1994	-26.769
1995	27.968
1996	27.764
1997	8.432
1998	-5.440
1999	26.806
2000	3.965
2001	13.854
2002	-6.072
2003	13.358
2004	9.402
2005	37.030
2006	2.045
2007	48.109
2008	45.626
2009	6.896
2010	-21.460
2011	11.016
2012	7.250
2013	8.461
2014	10.436
2015	-19.434
2016	-30.321
2017	5.708
2018	-11.171
2019	-11.251
2020	-32.646
2021	8.173
2022	42.126
2023	-13.033
2024	-5.753
2025	1.630
2026	0.986
2027	-7.801
2028	5.763
2029	-1.266