Year	Percent change (Units)
1980	21.348
1981	7.444
1982	4.069
1983	2.675
1984	2.004
1985	3.536
1986	3.036
1987	2.947
1988	5.188
1989	8.163
1990	4.637
1991	2.006
1992	4.314
1993	1.594
1994	-0.237
1995	1.398
1996	2.031
1997	2.173
1998	1.539
1999	-0.042
2000	1.108
2001	1.128
2002	0.358
2003	2.832
2004	0.818
2005	2.703
2006	1.795
2007	6.011
2008	2.016
2009	3.176
2010	0.048
2011	1.936
2012	1.266
2013	-0.440
2014	0.461
2015	-0.654
2016	0.718
2017	-1.484
2018	3.983
2019	0.143
2020	-0.704
2021	3.543
2022	8.688
2023	2.329
2024	2.182
2025	2.000
2026	2.000
2027	2.000
2028	2.000
2029	2.000