Year	Percent change (Units)
1987	3.639
1988	3.121
1989	3.989
1990	5.838
1991	5.553
1992	3.870
1993	5.219
1994	6.284
1995	3.413
1996	3.169
1997	3.006
1998	1.865
1999	2.274
2000	4.074
2001	2.884
2002	3.316
2003	3.655
2004	2.530
2005	3.397
2006	3.610
2007	5.390
2008	8.957
2009	-2.137
2010	2.078
2011	4.375
2012	0.572
2013	-2.372
2014	0.421
2015	0.475
2016	-0.932
2017	-1.028
2018	3.626
2019	3.939
2020	-1.313
2021	0.744
2022	5.520
2023	3.366
2024	2.345
2025	1.815
2026	1.914
2027	1.998
2028	1.998
2029	1.998