Year	Percent change (Units)
1980	-1.061
1981	5.244
1982	-4.988
1983	-33.125
1984	9.195
1985	5.857
1986	-7.484
1987	9.719
1988	-23.134
1989	3.390
1990	-0.839
1991	16.000
1992	1.000
1993	0.800
1994	14.636
1995	7.949
1996	-12.597
1997	20.513
1998	6.532
1999	-31.595
2000	12.822
2001	25.722
2002	19.015
2003	-4.060
2004	10.877
2005	13.162
2006	7.066
2007	6.166
2008	12.998
2009	-6.854
2010	12.479
2011	2.595
2012	0.214
2013	8.160
2014	4.687
2015	-4.790
2016	-12.158
2017	16.499
2018	3.572
2019	0.373
2020	-17.298
2021	19.058
2022	9.561
2023	2.801
2024	-1.426
2025	0.482
2026	1.291
2027	1.626
2028	2.016
2029	2.309