Year	Percent change (Units)
1980	12.064
1981	8.054
1982	5.535
1983	7.902
1984	7.421
1985	3.710
1986	5.454
1987	3.337
1988	5.445
1989	4.480
1990	6.953
1991	6.966
1992	4.310
1993	4.977
1994	2.849
1995	17.281
1996	11.632
1997	3.943
1998	13.590
1999	14.932
2000	15.596
2001	9.298
2002	11.799
2003	14.709
2004	2.159
2005	1.781
2006	2.368
2007	0.911
2008	10.767
2009	6.913
2010	5.102
2011	4.441
2012	4.537
2013	4.960
2014	5.222
2015	5.996
2016	6.674
2017	5.422
2018	4.412
2019	3.892
2020	4.872
2021	4.483
2022	5.253
2023	2.330
2024	4.200
2025	4.800
2026	4.800
2027	4.600
2028	4.500
2029	4.500