Year	Percent change (Units)
1980	18.483
1981	12.853
1982	-1.486
1983	10.085
1984	14.666
1985	6.776
1986	13.395
1987	28.534
1988	24.618
1989	8.435
1990	11.416
1991	17.689
1992	20.437
1993	11.887
1994	12.949
1995	12.169
1996	4.389
1997	6.923
1998	-5.727
1999	-0.511
2000	17.092
2001	-0.974
2002	7.042
2003	11.429
2004	14.398
2005	9.330
2006	9.903
2007	9.059
2008	3.247
2009	-8.033
2010	18.228
2011	5.603
2012	4.241
2013	8.282
2014	1.026
2015	-1.764
2016	0.868
2017	6.614
2018	4.487
2019	-7.245
2020	-6.858
2021	15.822
2022	-12.233
2023	-5.307
2024	4.979
2025	4.142
2026	3.990
2027	3.976
2028	3.904
2029	3.899