Year	Percent change (Units)
1980	3.718
1981	-9.542
1982	-9.009
1983	-2.728
1984	6.045
1985	35.866
1986	11.730
1987	15.791
1988	35.018
1989	2.119
1990	9.365
1991	9.365
1992	9.365
1993	9.365
1994	5.037
1995	8.911
1996	9.875
1997	23.148
1998	25.868
1999	11.669
2000	-3.771
2001	3.292
2002	6.485
2003	3.502
2004	10.406
2005	9.730
2006	9.225
2007	10.231
2008	3.157
2009	-9.578
2010	6.983
2011	6.127
2012	3.288
2013	4.100
2014	4.300
2015	4.154
2016	3.059
2017	5.451
2018	3.588
2019	1.405
2020	-11.898
2021	10.947
2022	8.810
2023	1.457
2024	3.787
2025	4.097
2026	4.218
2027	3.810
2028	3.844
2029	3.736