Year	Percent change (Units)
1980	26.646
1981	4.207
1982	3.549
1983	-15.437
1984	-14.872
1985	-22.794
1986	-20.727
1987	4.253
1988	-7.840
1989	2.851
1990	-6.350
1991	3.209
1992	10.807
1993	-8.055
1994	-5.595
1995	37.027
1996	14.082
1997	27.585
1998	1.510
1999	1.474
2000	22.488
2001	5.622
2002	-3.961
2003	49.374
2004	17.105
2005	51.906
2006	57.999
2007	25.307
2008	5.918
2009	-10.865
2010	-1.425
2011	40.790
2012	21.606
2013	8.707
2014	6.040
2015	-9.164
2016	5.196
2017	-3.471
2018	4.600
2019	1.870
2020	-8.871
2021	1.627
2022	4.200
2023	1.558
2024	1.994
2025	1.991
2026	5.872
2027	7.564
2028	3.433
2029	1.607