Year	Percent change (Units)
1980	20.017
1981	36.797
1982	23.123
1983	-8.882
1984	-8.770
1985	-6.008
1986	10.116
1987	4.906
1988	3.758
1989	-2.659
1990	9.149
1991	-21.170
1992	24.766
1993	44.869
1994	16.759
1995	6.719
1996	1.389
1997	18.612
1998	1.123
1999	-23.694
2000	15.145
2001	8.740
2002	0.329
2003	8.170
2004	10.272
2005	11.902
2006	17.683
2007	13.857
2008	12.512
2009	-8.648
2010	10.829
2011	20.230
2012	9.376
2013	8.523
2014	7.759
2015	-1.080
2016	-3.541
2017	1.019
2018	5.805
2019	7.343
2020	-20.093
2021	26.729
2022	23.614
2023	-12.203
2024	1.128
2025	2.851
2026	3.103
2027	3.169
2028	2.614
2029	2.449