Year	Percent change (Units)
1980	24.873
1981	24.463
1982	21.125
1983	20.179
1984	18.456
1985	19.315
1986	23.017
1987	16.397
1988	13.518
1989	13.702
1990	20.434
1991	19.456
1992	15.877
1993	14.411
1994	10.873
1995	8.788
1996	7.873
1997	5.441
1998	4.517
1999	2.141
2000	2.897
2001	3.642
2002	3.921
2003	3.450
2004	3.020
2005	3.486
2006	3.314
2007	2.989
2008	4.230
2009	1.347
2010	4.704
2011	3.118
2012	1.035
2013	-0.854
2014	-1.394
2015	-1.094
2016	0.013
2017	1.138
2018	0.774
2019	0.517
2020	-1.262
2021	0.574
2022	9.300
2023	4.155
2024	2.749
2025	2.096
2026	1.992
2027	1.900
2028	1.894
2029	1.894