Year	Percent change (Units)
1981	4.558
1982	13.431
1983	13.547
1984	16.591
1985	3.658
1986	8.541
1987	18.896
1988	-1.878
1989	0.000
1990	-0.734
1991	-0.230
1992	0.751
1993	-4.056
1994	33.786
1995	16.239
1996	0.799
1997	4.627
1998	5.938
1999	-0.477
2000	1.498
2001	4.959
2002	2.362
2003	-0.055
2004	1.008
2005	3.465
2006	2.420
2007	3.441
2008	5.313
2009	0.943
2010	2.569
2011	2.732
2012	2.534
2013	1.646
2014	2.621
2015	1.446
2016	0.292
2017	0.762
2018	1.974
2019	2.427
2020	2.119
2021	3.457
2022	7.315
2023	5.980
2024	5.500
2025	5.200
2026	3.557
2027	2.000
2028	2.000
2029	2.000