Year	Percent change (Units)
1980	6.615
1981	-6.143
1982	16.617
1983	-21.712
1984	-23.231
1985	19.021
1986	-29.919
1987	22.753
1988	-9.967
1989	-2.778
1990	-6.571
1991	-11.164
1992	-10.971
1993	2.932
1994	54.476
1995	-37.100
1996	1.480
1997	2.231
1998	2.508
1999	-8.999
2000	7.458
2001	9.656
2002	0.766
2003	0.002
2004	6.612
2005	6.692
2006	-0.774
2007	4.911
2008	33.219
2009	32.222
2010	11.503
2011	3.130
2012	-4.312
2013	5.693
2014	4.990
2015	7.367
2016	-14.536
2017	11.810
2018	7.116
2019	8.174
2020	27.245
2021	-3.537
2022	-8.124
2023	6.426
2024	21.891
2025	7.484
2026	6.728
2027	6.260
2028	7.503
2029	6.824