Year	Percent change (Units)
1980	14.933
1981	-2.520
1982	15.933
1983	22.781
1984	21.354
1985	28.916
1986	-6.746
1987	2.171
1988	-3.253
1989	23.584
1990	1.992
1991	-4.079
1992	5.337
1993	-16.500
1994	-11.018
1995	1.642
1996	7.421
1997	13.767
1998	11.130
1999	8.158
2000	-9.945
2001	-1.749
2002	-4.302
2003	14.445
2004	0.198
2005	-2.937
2006	1.300
2007	19.067
2008	-2.744
2009	7.408
2010	-9.840
2011	10.420
2012	-0.946
2013	11.313
2014	16.170
2015	14.125
2016	-4.134
2017	-1.369
2018	-0.694
2019	-1.413
2020	-5.932
2021	14.064
2022	7.534
2023	4.177
2024	3.369
2025	5.957
2026	6.929
2027	4.480
2028	6.803
2029	7.336