Year	Percent change (Units)
1980	12.199
1981	5.200
1982	2.400
1983	-22.600
1984	16.900
1985	-14.100
1986	36.300
1987	15.000
1988	11.900
1989	-14.200
1990	43.100
1991	4.200
1992	-6.670
1993	8.496
1994	10.337
1995	23.634
1996	-17.684
1997	-14.805
1998	-13.301
1999	-30.857
2000	-11.233
2001	-19.430
2002	-24.263
2003	11.800
2004	20.741
2005	4.175
2006	15.208
2007	21.286
2008	27.885
2009	-22.440
2010	40.426
2011	16.157
2012	-11.432
2013	6.140
2014	-2.143
2015	-17.559
2016	-7.486
2017	14.500
2018	7.264
2019	-9.549
2020	-18.581
2021	20.336
2022	2.997
2023	6.198
2024	2.077
2025	1.486
2026	1.682
2027	1.884
2028	2.061
2029	2.348