Year	Percent change (Units)
1988	9.616
1989	3.327
1990	1.118
1991	7.592
1992	7.069
1993	4.042
1994	8.181
1995	5.979
1996	5.898
1997	4.007
1998	4.682
1999	12.705
2000	9.575
2001	7.390
2002	6.265
2003	10.284
2004	9.458
2005	13.303
2006	10.943
2007	10.398
2008	7.476
2009	4.075
2010	5.077
2011	7.287
2012	7.650
2013	7.857
2014	8.000
2015	7.207
2016	7.906
2017	8.075
2018	8.776
2019	7.937
2020	-3.556
2021	3.090
2022	5.103
2023	4.998
2024	6.032
2025	6.119
2026	6.092
2027	5.953
2028	5.763
2029	5.501