Year	Percent change (Units)
1981	27.040
1982	20.184
1983	46.250
1984	94.642
1985	54.101
1986	78.517
1987	96.877
1988	50.320
1989	66.839
1990	32.138
1991	60.099
1992	86.697
1993	30.700
1994	19.277
1995	49.669
1996	65.590
1997	16.738
1998	7.936
1999	-7.922
2000	16.684
2001	-1.888
2002	2.519
2003	0.727
2004	2.887
2005	0.301
2006	3.197
2007	9.293
2008	8.680
2009	-6.357
2010	5.703
2011	3.448
2012	1.619
2013	-0.094
2014	-0.094
2015	2.441
2016	0.871
2017	-0.483
2018	2.398
2019	-0.095
2020	1.499
2021	5.844
2022	9.452
2023	3.067
2024	3.000
2025	2.000
2026	2.000
2027	2.000
2028	2.000
2029	2.000