Year	Percent change (Units)
1980	-0.646
1981	3.051
1982	-4.229
1983	3.281
1984	9.413
1985	-6.239
1986	3.628
1987	20.949
1988	7.370
1989	16.074
1990	7.901
1991	10.059
1992	17.774
1993	9.112
1994	4.148
1995	8.998
1996	6.658
1997	8.256
1998	25.561
1999	19.402
2000	3.546
2001	1.702
2002	2.680
2003	5.671
2004	10.383
2005	6.012
2006	8.041
2007	7.523
2008	2.172
2009	-8.462
2010	9.327
2011	7.048
2012	5.564
2013	3.312
2014	4.964
2015	2.888
2016	9.417
2017	6.955
2018	4.891
2019	4.261
2020	-10.633
2021	15.934
2022	13.207
2023	10.460
2024	8.256
2025	6.278
2026	6.233
2027	6.225
2028	6.237
2029	6.209