Year	Percent change (Units)
1980	8.250
1981	13.144
1982	12.998
1983	6.950
1984	10.922
1985	9.409
1986	13.100
1987	11.494
1988	16.812
1989	14.936
1990	8.700
1991	15.000
1992	10.800
1993	9.200
1994	13.294
1995	9.612
1996	11.773
1997	8.065
1998	12.355
1999	7.953
2000	6.928
2001	7.628
2002	9.366
2003	10.077
2004	6.916
2005	7.530
2006	11.235
2007	7.654
2008	17.338
2009	7.166
2010	0.905
2011	7.418
2012	5.914
2013	5.249
2014	5.296
2015	-0.569
2016	0.497
2017	0.503
2018	3.475
2019	1.635
2020	2.964
2021	-0.108
2022	5.507
2023	4.490
2024	3.495
2025	3.203
2026	3.085
2027	3.074
2028	3.006
2029	3.040