Year	Percent change (Units)
1980	3.266
1981	0.500
1982	0.600
1983	2.400
1984	3.400
1985	4.600
1986	6.600
1987	5.900
1988	4.400
1989	3.800
1990	7.045
1991	2.072
1992	0.584
1993	1.206
1994	1.567
1995	3.571
1996	4.544
1997	3.525
1998	3.708
1999	4.840
2000	4.934
2001	5.998
2002	7.164
2003	6.886
2004	7.828
2005	7.370
2006	4.661
2007	8.464
2008	5.567
2009	5.382
2010	6.359
2011	7.905
2012	5.141
2013	6.782
2014	6.732
2015	6.161
2016	6.867
2017	6.727
2018	7.028
2019	6.915
2020	4.535
2021	4.838
2022	4.680
2023	5.023
2024	5.503
2025	5.999
2026	6.298
2027	6.496
2028	6.496
2029	6.502