Year	Percent change (Units)
1980	33.900
1981	18.868
1982	-35.687
1983	-36.991
1984	18.457
1985	12.370
1986	-7.596
1987	3.625
1988	36.702
1989	18.438
1990	19.498
1991	15.283
1992	19.864
1993	16.033
1994	18.096
1995	-17.497
1996	18.103
1997	23.554
1998	14.428
1999	11.775
2000	21.031
2001	-0.298
2002	3.614
2003	3.012
2004	7.027
2005	5.926
2006	7.707
2007	5.743
2008	3.812
2009	-16.387
2010	17.111
2011	6.235
2012	5.648
2013	3.630
2014	5.962
2015	4.949
2016	2.534
2017	5.649
2018	5.604
2019	-1.081
2020	-11.991
2021	15.050
2022	8.305
2023	5.715
2024	1.679
2025	2.710
2026	2.835
2027	3.063
2028	3.063
2029	3.071