Year	Percent change (Units)
1980	23.082
1981	10.306
1982	22.944
1983	-12.553
1984	-6.818
1985	-7.088
1986	0.727
1987	1.810
1988	12.621
1989	-2.449
1990	10.617
1991	-5.006
1992	24.650
1993	44.905
1994	21.316
1995	7.877
1996	1.389
1997	18.612
1998	1.123
1999	-23.694
2000	11.056
2001	14.781
2002	-1.126
2003	3.785
2004	9.616
2005	18.791
2006	16.401
2007	16.270
2008	6.161
2009	-9.914
2010	11.505
2011	22.741
2012	9.140
2013	3.857
2014	12.339
2015	-6.018
2016	-12.540
2017	-0.840
2018	8.344
2019	1.591
2020	-15.954
2021	16.230
2022	13.201
2023	-12.203
2024	1.128
2025	2.851
2026	3.103
2027	3.169
2028	2.614
2029	2.449