Year	Percent change (Units)
1980	7.065
1981	1.705
1982	4.482
1983	10.520
1984	16.246
1985	6.600
1986	2.710
1987	13.879
1988	8.151
1989	11.417
1990	9.173
1991	5.610
1992	13.859
1993	9.812
1994	15.101
1995	20.141
1996	12.421
1997	17.549
1998	22.771
1999	15.772
2000	21.187
2001	14.008
2002	6.476
2003	-1.698
2004	6.521
2005	5.480
2006	6.051
2007	8.901
2008	-3.804
2009	4.648
2010	5.983
2011	3.108
2012	-0.822
2013	2.991
2014	14.592
2015	39.166
2016	4.603
2017	9.635
2018	9.805
2019	11.848
2020	11.531
2021	15.103
2022	13.922
2023	-4.762
2024	3.000
2025	3.000
2026	3.200
2027	3.200
2028	3.200
2029	3.200