Year	Percent change (Units)
1980	9.880
1981	7.604
1982	2.246
1983	4.193
1984	7.574
1985	3.906
1986	7.189
1987	6.572
1988	6.979
1989	9.085
1990	9.002
1991	8.928
1992	6.523
1993	7.956
1994	7.540
1995	8.220
1996	7.818
1997	4.700
1998	-13.127
1999	0.791
2000	4.979
2001	3.643
2002	4.499
2003	4.780
2004	5.031
2005	5.693
2006	5.501
2007	6.345
2008	7.442
2009	4.702
2010	6.378
2011	6.170
2012	6.030
2013	5.557
2014	5.007
2015	4.876
2016	5.033
2017	5.070
2018	5.174
2019	5.019
2020	-2.066
2021	3.703
2022	5.307
2023	5.048
2024	4.964
2025	5.055
2026	5.056
2027	5.055
2028	5.069
2029	5.071