Year	Percent change (Units)
1980	14.774
1981	20.143
1982	33.229
1983	12.790
1984	11.100
1985	7.510
1986	-9.888
1987	6.243
1988	0.485
1989	28.021
1990	-6.150
1991	3.400
1992	23.500
1993	62.700
1994	30.600
1995	4.400
1996	17.114
1997	-6.043
1998	-14.700
1999	0.268
2000	23.200
2001	6.894
2002	-2.110
2003	1.819
2004	33.636
2005	12.612
2006	20.606
2007	20.257
2008	22.166
2009	8.530
2010	10.499
2011	16.967
2012	22.987
2013	12.340
2014	15.582
2015	-15.835
2016	-0.517
2017	2.150
2018	7.782
2019	-1.556
2020	-11.164
2021	0.389
2022	4.074
2023	1.912
2024	-0.582
2025	0.168
2026	2.328
2027	7.576
2028	7.077
2029	7.128