Year	Percent change (Units)
1980	17.111
1981	7.323
1982	10.027
1983	11.969
1984	9.125
1985	4.437
1986	9.150
1987	9.281
1988	5.479
1989	6.234
1990	9.780
1991	10.022
1992	5.061
1993	10.212
1994	9.703
1995	8.924
1996	5.999
1997	10.352
1998	77.611
1999	1.901
2000	9.330
2001	12.579
2002	9.938
2003	5.186
2004	6.385
2005	17.144
2006	6.593
2007	5.780
2008	11.062
2009	2.779
2010	6.953
2011	3.785
2012	3.647
2013	8.088
2014	8.360
2015	3.353
2016	3.027
2017	3.605
2018	3.163
2019	2.585
2020	1.676
2021	1.879
2022	5.411
2023	2.806
2024	2.513
2025	2.551
2026	2.523
2027	2.515
2028	2.512
2029	2.512