Year	Percent change (Units)
1981	6.967
1982	16.210
1983	7.997
1984	23.869
1985	8.362
1986	-5.579
1987	17.980
1988	-6.403
1989	-10.300
1990	0.000
1991	0.000
1992	0.000
1993	0.000
1994	-15.704
1995	9.271
1996	3.214
1997	20.036
1998	9.927
1999	17.647
2000	2.810
2001	-0.690
2002	9.513
2003	1.362
2004	11.707
2005	44.354
2006	18.549
2007	3.365
2008	16.570
2009	32.278
2010	23.173
2011	-6.291
2012	25.936
2013	4.414
2014	17.905
2015	32.461
2016	12.958
2017	-4.609
2018	-8.182
2019	-3.203
2020	-3.477
2021	-0.707
2022	8.785
2023	-8.994
2024	12.189
2025	3.360
2026	14.959
2027	10.283
2028	10.015
2029	7.728