Year	Percent change (Units)
1980	9.666
1981	12.119
1982	-1.352
1983	-7.587
1984	-14.920
1985	-4.134
1986	-1.411
1987	0.878
1988	6.977
1989	19.800
1990	16.000
1991	19.251
1992	27.519
1993	16.235
1994	9.236
1995	1.212
1996	4.566
1997	17.962
1998	0.874
1999	0.673
2000	9.855
2001	11.969
2002	11.235
2003	15.142
2004	26.506
2005	10.723
2006	6.889
2007	40.749
2008	23.125
2009	-14.140
2010	-1.919
2011	11.406
2012	11.015
2013	10.880
2014	6.007
2015	2.765
2016	3.355
2017	0.871
2018	-5.910
2019	-3.558
2020	-12.521
2021	5.544
2022	15.505
2023	11.975
2024	2.610
2025	2.854
2026	2.884
2027	3.412
2028	3.645
2029	4.438