Year	Percent change (Units)
1980	9.800
1981	13.447
1982	10.381
1983	14.197
1984	6.214
1985	4.127
1986	15.854
1987	13.285
1988	11.024
1989	8.078
1990	8.926
1991	7.943
1992	21.061
1993	8.871
1994	8.951
1995	7.677
1996	7.179
1997	8.101
1998	8.326
1999	11.379
2000	3.393
2001	2.435
2002	2.896
2003	4.743
2004	3.963
2005	4.539
2006	7.963
2007	6.203
2008	6.677
2009	12.624
2010	9.565
2011	9.566
2012	8.305
2013	9.873
2014	9.039
2015	7.212
2016	9.932
2017	4.454
2018	4.147
2019	4.639
2020	6.150
2021	3.599
2022	6.261
2023	7.815
2024	6.312
2025	5.613
2026	5.450
2027	5.400
2028	5.400
2029	5.400