Year	Percent change (Units)
1980	21.175
1981	19.507
1982	16.504
1983	14.672
1984	10.725
1985	9.241
1986	5.850
1987	4.692
1988	5.102
1989	6.264
1990	9.309
1991	5.671
1992	4.651
1993	4.444
1994	4.092
1995	5.660
1996	2.976
1997	1.734
1998	1.705
1999	2.095
2000	2.736
2001	2.264
2002	2.995
2003	2.528
2004	2.343
2005	2.048
2006	2.125
2007	2.775
2008	2.362
2009	1.099
2010	2.065
2011	3.727
2012	2.567
2013	0.601
2014	0.000
2015	0.100
2016	0.497
2017	0.989
2018	1.175
2019	0.484
2020	-0.289
2021	4.155
2022	12.338
2023	0.495
2024	2.199
2025	1.872
2026	2.000
2027	2.000
2028	2.000
2029	2.000