Year	Percent change (Units)
1980	0.599
1981	1.625
1982	-0.516
1983	6.363
1984	20.282
1985	4.384
1986	4.045
1987	3.393
1988	9.269
1989	0.488
1990	4.963
1991	1.798
1992	7.730
1993	11.144
1994	13.008
1995	9.086
1996	5.540
1997	8.914
1998	8.717
1999	11.550
2000	9.046
2001	-3.155
2002	0.629
2003	-1.776
2004	5.332
2005	2.107
2006	0.789
2007	1.369
2008	-5.325
2009	-14.792
2010	8.363
2011	4.960
2012	2.581
2013	2.534
2014	6.226
2015	3.387
2016	0.610
2017	0.841
2018	2.451
2019	0.323
2020	-7.723
2021	1.714
2022	2.349
2023	4.376
2024	2.686
2025	2.559
2026	3.368
2027	3.436
2028	3.214
2029	2.943