Year	Percent change (Units)
1980	16.019
1981	9.385
1982	-14.564
1983	10.901
1984	3.303
1985	-12.499
1986	49.154
1987	13.874
1988	19.873
1989	26.521
1990	-6.939
1991	-7.277
1992	-10.282
1993	-10.981
1994	-10.115
1995	-2.800
1996	-6.282
1997	31.763
1998	15.217
1999	-5.305
2000	-1.909
2001	-1.592
2002	2.063
2003	-7.264
2004	17.706
2005	-5.006
2006	-1.371
2007	32.404
2008	39.685
2009	-8.574
2010	11.020
2011	11.107
2012	25.259
2013	14.308
2014	-1.320
2015	5.836
2016	-20.922
2017	-12.949
2018	15.917
2019	11.572
2020	4.952
2021	2.344
2022	-11.775
2023	-10.214
2024	8.591
2025	9.098
2026	11.864
2027	6.119
2028	5.879
2029	5.908