Year	Percent change (Units)
1980	15.191
1981	14.399
1982	14.009
1983	12.235
1984	9.009
1985	8.178
1986	8.261
1987	4.593
1988	5.844
1989	6.893
1990	6.542
1991	5.524
1992	5.360
1993	4.926
1994	4.336
1995	4.320
1996	3.273
1997	1.879
1998	1.358
1999	2.778
2000	4.007
2001	2.512
2002	4.012
2003	2.692
2004	3.277
2005	3.722
2006	2.718
2007	4.284
2008	1.450
2009	0.899
2010	2.865
2011	2.347
2012	3.007
2013	0.307
2014	-1.134
2015	-0.130
2016	1.409
2017	1.222
2018	1.226
2019	0.846
2020	-0.572
2021	6.569
2022	5.480
2023	3.276
2024	2.435
2025	2.204
2026	1.894
2027	1.800
2028	1.800
2029	1.800