Year	Percent change (Units)
1980	19.023
1981	10.863
1982	2.952
1983	1.370
1984	-0.031
1985	-0.162
1986	0.699
1987	0.510
1988	1.289
1989	4.416
1990	4.129
1991	3.623
1992	4.462
1993	2.944
1994	4.098
1995	3.666
1996	3.077
1997	0.905
1998	1.684
1999	0.175
2000	1.248
2001	-0.003
2002	-0.196
2003	-0.281
2004	1.608
2005	2.309
2006	0.600
2007	1.796
2008	3.530
2009	-0.875
2010	0.966
2011	1.421
2012	1.935
2013	0.792
2014	1.194
2015	-0.306
2016	1.393
2017	0.622
2018	1.350
2019	0.559
2020	-0.238
2021	1.971
2022	2.947
2023	2.492
2024	1.881
2025	1.555
2026	1.511
2027	1.517
2028	1.587
2029	1.491