Year	Percent change (Units)
1980	0.789
1981	11.283
1982	5.573
1983	9.613
1984	12.036
1985	0.669
1986	0.230
1987	5.269
1988	3.815
1989	1.428
1990	4.694
1991	8.252
1992	7.503
1993	7.839
1994	16.670
1995	8.310
1996	10.318
1997	14.990
1998	8.018
1999	7.479
2000	10.244
2001	3.938
2002	1.431
2003	3.565
2004	4.306
2005	1.890
2006	4.730
2007	7.599
2008	-0.907
2009	-10.839
2010	9.064
2011	8.176
2012	0.930
2013	4.384
2014	4.523
2015	4.316
2016	5.372
2017	5.514
2018	1.723
2019	2.213
2020	-20.054
2021	13.496
2022	15.154
2023	2.322
2024	3.047
2025	3.877
2026	3.068
2027	3.150
2028	3.159
2029	3.165
