Year	Percent change (Units)
1980	15.067
1981	1.375
1982	4.107
1983	3.295
1984	3.963
1985	5.988
1986	7.358
1987	9.073
1988	2.916
1989	3.758
1990	4.241
1991	1.423
1992	-0.813
1993	-1.956
1994	1.838
1995	2.196
1996	4.386
1997	4.916
1998	11.808
1999	6.981
2000	5.063
2001	-2.024
2002	3.438
2003	9.464
2004	-0.647
2005	13.273
2006	-3.993
2007	6.124
2008	0.948
2009	-6.613
2010	-0.511
2011	0.765
2012	-1.155
2013	2.351
2014	7.342
2015	6.445
2016	3.740
2017	4.439
2018	4.361
2019	0.677
2020	-13.757
2021	4.687
2022	7.321
2023	4.791
2024	4.141
2025	3.672
2026	2.977
2027	2.700
2028	2.703
2029	2.706