Year	Percent change (Units)
1980	5.140
1981	11.460
1982	17.581
1983	14.537
1984	14.686
1985	13.744
1986	8.293
1987	9.549
1988	12.473
1989	21.337
1990	11.302
1991	-5.030
1992	2.804
1993	10.043
1994	14.613
1995	19.203
1996	11.129
1997	10.526
1998	17.817
1999	-6.652
2000	-2.090
2001	16.748
2002	-7.277
2003	8.519
2004	3.497
2005	11.631
2006	7.583
2007	12.176
2008	15.007
2009	10.070
2010	0.561
2011	41.754
2012	0.083
2013	3.603
2014	10.279
2015	11.506
2016	12.989
2017	6.374
2018	19.347
2019	2.464
2020	-2.475
2021	6.071
2022	20.114
2023	-12.432
2024	4.111
2025	17.972
2026	9.576
2027	8.986
2028	10.620
2029	11.533