Year	Percent change (Units)
1980	13.739
1981	22.364
1982	10.872
1983	-7.010
1984	-0.783
1985	-2.333
1986	11.876
1987	1.553
1988	-13.299
1989	-14.551
1990	67.848
1991	3.848
1992	-54.153
1993	57.583
1994	-33.723
1995	153.296
1996	-5.767
1997	14.676
1998	28.326
1999	17.685
2000	-2.330
2001	2.403
2002	-5.682
2003	8.209
2004	-1.822
2005	-1.978
2006	12.565
2007	5.385
2008	11.525
2009	4.045
2010	39.305
2011	1.189
2012	-9.124
2013	11.370
2014	30.833
2015	10.003
2016	-10.229
2017	7.421
2018	8.930
2019	-7.160
2020	-5.011
2021	3.085
2022	-6.095
2023	3.768
2024	-3.061
2025	6.191
2026	2.039
2027	2.120
2028	2.122
2029	2.122