Year	Percent change (Units)
1980	10.493
1981	8.463
1982	2.583
1983	1.605
1984	-6.498
1985	7.296
1986	-4.757
1987	1.251
1988	12.721
1989	-6.067
1990	10.358
1991	10.727
1992	13.246
1993	7.409
1994	5.534
1995	5.423
1996	2.966
1997	-1.090
1998	5.554
1999	-3.121
2000	2.295
2001	3.680
2002	5.897
2003	-2.037
2004	6.903
2005	6.215
2006	5.046
2007	5.675
2008	4.477
2009	5.912
2010	3.440