Year	Percent change (Units)
1980	-1.016
1981	-3.894
1982	-8.210
1983	-5.329
1984	15.988
1985	-13.031
1986	3.706
1987	0.900
1988	4.700
1989	5.300
1990	-14.644
1991	-1.524
1992	10.424
1993	-0.891
1994	1.929
1995	0.361
1996	4.229
1997	27.745
1998	10.253
1999	3.767
2000	6.946
2001	4.500
2002	6.873
2003	3.987
2004	19.225
2005	7.792
2006	28.082
2007	18.191
2008	17.494
2009	13.063
2010	17.746
2011	11.302
2012	4.730
2013	5.556
2014	5.334
2015	4.753
2016	3.064
2017	-1.498
2018	1.235
2019	0.688
2020	-3.558
2021	1.627
2022	4.200
2023	1.558
2024	1.994
2025	1.991
2026	5.872
2027	7.564
2028	3.433
2029	1.607