Year	Percent change (Units)
1980	9.255
1981	1.929
1982	1.682
1983	-2.000
1984	0.400
1985	4.327
1986	2.748
1987	-2.074
1988	3.428
1989	-2.849
1990	8.976
1991	4.226
1992	2.958
1993	5.836
1994	2.020
1995	6.045
1996	4.324
1997	5.735
1998	3.961
1999	4.358
2000	5.858
2001	5.333
2002	4.643
2003	3.444
2004	4.430
2005	1.713
2006	3.944
2007	5.986
2008	4.897
2009	2.319
2010	2.114
2011	2.964
2012	4.811
2013	7.191
2014	6.358
2015	1.778
2016	3.340
2017	5.672
2018	6.697
2019	6.866
2020	3.849
2021	7.155
2022	6.253
2023	5.756
2024	6.039
2025	6.020
2026	5.989
2027	6.028
2028	6.037
2029	6.026