Year	Percent change (Units)
1980	12.437
1981	1.937
1982	7.774
1983	3.569
1984	-0.334
1985	18.403
1986	5.550
1987	-9.146
1988	2.206
1989	9.633
1990	5.206
1991	20.869
1992	21.019
1993	9.990
1994	1.166
1995	13.354
1996	0.919
1997	-6.420
1998	3.600
1999	7.941
2000	0.662
2001	-8.238
2002	1.654
2003	17.762
2004	3.221
2005	11.656
2006	13.558
2007	17.245
2008	44.371
2009	8.479
2010	8.134
2011	33.232
2012	24.132
2013	8.071
2014	7.404
2015	9.569
2016	6.628
2017	10.687
2018	13.833
2019	15.810
2020	20.354
2021	26.794
2022	33.938
2023	30.219
2024	25.572
2025	18.187
2026	14.281
2027	14.281
2028	14.281
2029	14.281