Year	Percent change (Units)
1980	10.720
1981	23.169
1982	22.679
1983	-4.569
1984	-11.858
1985	-25.994
1986	-19.660
1987	-2.536
1988	-2.689
1989	-4.388
1990	10.673
1991	18.083
1992	18.321
1993	-14.019
1994	-19.954
1995	14.410
1996	-2.951
1997	8.888
1998	9.224
1999	-3.436
2000	7.868
2001	6.092
2002	4.043
2003	9.651
2004	11.963
2005	26.052
2006	10.341
2007	22.136
2008	12.117
2009	-10.937
2010	2.425
2011	14.308
2012	18.915
2013	11.339
2014	6.513
2015	8.586
2016	-16.514
2017	-5.508
2018	0.252
2019	10.089
2020	-9.496
2021	0.372
2022	14.265
2023	15.426
2024	12.708
2025	14.312
2026	5.931
2027	4.150
2028	2.849
2029	4.211