Year	Percent change (Units)
1980	14.143
1981	6.632
1982	5.251
1983	12.695
1984	10.662
1985	12.458
1986	11.891
1987	3.168
1988	8.637
1989	10.718
1990	47.373
1991	25.900
1992	31.700
1993	20.500
1994	29.000
1995	29.800
1996	18.700
1997	5.700
1998	4.950
1999	2.600
2000	0.300
2001	4.200
2002	2.100
2003	5.563
2004	2.190
2005	1.226
2006	3.839
2007	4.803
2008	4.863
2009	5.753
2010	2.725
2011	5.160
2012	9.035
2013	1.148
2014	5.253
2015	4.362
2016	6.957
2017	4.933
2018	2.702
2019	2.434
2020	3.516
2021	8.485
2022	9.295
2023	7.838
2024	6.968
2025	6.090
2026	5.854
2027	5.307
2028	5.066
2029	4.994