Year	Percent change (Units)
1980	5.013
1981	0.214
1982	-7.551
1983	6.076
1984	11.332
1985	-1.419
1986	7.275
1987	21.997
1988	10.861
1989	15.474
1990	11.209
1991	11.464
1992	12.041
1993	6.275
1994	0.158
1995	0.640
1996	1.062
1997	3.588
1998	3.889
1999	8.972
2000	13.023
2001	5.012
2002	5.121
2003	9.326
2004	4.650
2005	2.360
2006	4.377
2007	3.295
2008	-1.539
2009	-0.447
2010	1.238
2011	-0.298
2012	3.661
2013	4.437
2014	4.006
2015	3.226
2016	-0.009
2017	-1.817
2018	1.056
2019	4.236
2020	-13.731
2021	17.864
2022	8.733
2023	4.699
2024	3.383
2025	2.544
2026	2.544
2027	2.544
2028	2.544
2029	2.544