Year	Percent change (Units)
1980	-1.200
1981	-8.100
1982	-15.400
1983	-1.300
1984	-1.200
1985	39.200
1986	-10.900
1987	18.200
1988	-3.200
1989	5.200
1990	8.223
1991	15.469
1992	15.799
1993	28.120
1994	23.384
1995	-19.162
1996	10.401
1997	-11.841
1998	0.774
1999	11.434
2000	0.240
2001	19.982
2002	5.840
2003	12.843
2004	5.449
2005	5.788
2006	-25.463
2007	14.924
2008	18.457
2009	14.145
2010	5.364