Year	Percent change (Units)
1980	-1.646
1981	7.246
1982	8.338
1983	13.376
1984	10.552
1985	7.839
1986	11.327
1987	12.724
1988	11.988
1989	7.073
1990	9.878
1991	10.778
1992	6.199
1993	6.877
1994	9.269
1995	9.615
1996	7.891
1997	6.171
1998	-5.129
1999	11.467
2000	9.061
2001	4.852
2002	7.725
2003	3.147
2004	5.197
2005	4.309
2006	5.264
2007	5.800
2008	3.013
2009	0.793
2010	6.805
2011	3.686
2012	2.403
2013	3.165
2014	3.202
2015	2.809
2016	2.947
2017	3.160
2018	2.907
2019	2.244
2020	-0.709
2021	4.305
2022	2.613
2023	1.357
2024	2.322
2025	2.337
2026	2.212
2027	2.131
2028	2.084
2029	2.025