Year	Percent change (Units)
1980	11.339
1981	11.718
1982	10.146
1983	6.835
1984	6.343
1985	4.662
1986	3.718
1987	3.979
1988	4.525
1989	4.780
1990	2.648
1991	2.167
1992	1.944
1993	0.872
1994	1.841
1995	2.038
1996	2.092
1997	1.933
1998	1.314
1999	2.041
2000	2.751
2001	2.269
2002	2.397
2003	1.961
2004	0.937
2005	1.726
2006	1.844
2007	1.657
2008	3.638
2009	1.042
2010	2.198
2011	2.656
2012	2.354
2013	0.522
2014	0.352
2015	0.226
2016	0.017
2017	1.058
2018	0.709
2019	0.729
2020	0.333
2021	1.944
2022	8.534
2023	3.353
2024	1.459
2025	1.987
2026	2.000
2027	2.000
2028	2.000
2029	2.000