Year	Percent change (Units)
1987	3.319
1988	11.073
1989	12.588
1990	5.587
1991	9.186
1992	2.731
1993	4.758
1994	7.690
1995	4.571
1996	2.271
1997	11.367
1998	11.173
1999	14.251
2000	17.131
2001	6.417
2002	-0.098
2003	2.783
2004	9.232
2005	5.977
2006	12.922
2007	5.128
2008	-0.328
2009	-7.243
2010	10.156
2011	4.388
2012	1.619
2013	6.316
2014	6.516
2015	5.139
2016	5.309
2017	-0.227
2018	3.612
2019	5.996
2020	0.594
2021	10.278
2022	-0.641
2023	-1.367
2024	1.180
2025	2.500
2026	2.450
2027	2.400
2028	2.400
2029	2.400