Year	Percent change (Units)
1980	-2.580
1981	-2.792
1982	-5.159
1983	-7.481
1984	5.487
1985	2.575
1986	14.732
1987	-6.834
1988	-2.965
1989	-9.211
1990	4.890
1991	-3.677
1992	13.454
1993	20.465
1994	29.422
1995	-51.056
1996	4.701
1997	36.394
1998	-5.487
1999	4.264
2000	-22.487
2001	3.641
2002	9.623
2003	2.091
2004	12.402
2005	21.340
2006	26.162
2007	31.556
2008	28.771
2009	20.711
2010	4.169
2011	15.611
2012	29.123
2013	-0.806
2014	10.000
2015	12.423
2016	-5.304
2017	12.627
2018	10.678
2019	8.567
2020	2.775
2021	3.984
2022	12.983
2023	17.903
2024	2.832
2025	3.302
2026	4.363
2027	4.423
2028	2.834
2029	2.802