Year	Percent change (Units)
1980	21.450
1981	9.463
1982	0.553
1983	1.324
1984	1.534
1985	0.990
1986	4.510
1987	5.066
1988	1.607
1989	3.779
1990	6.012
1991	6.310
1992	3.156
1993	0.728
1994	5.857
1995	4.645
1996	-2.285
1997	1.937
1998	3.604
1999	1.999
2000	6.892
2001	2.974
2002	-0.676
2003	0.510
2004	3.499
2005	5.180
2006	0.675
2007	6.794
2008	3.404
2009	-3.091
2010	4.226
2011	4.784
2012	5.009
2013	-0.746
2014	3.670
2015	-2.604
2016	-2.834
2017	1.979
2018	2.170
2019	-0.703
2020	-0.367
2021	4.148
2022	6.901
2023	2.206
2024	1.830
2025	2.000
2026	2.000
2027	2.000
2028	2.000
2029	2.000