Year	Percent change (Units)
1980	31.430
1981	2.025
1982	-15.635
1983	-12.018
1984	-11.027
1985	-0.769
1986	32.434
1987	19.956
1988	5.042
1989	31.508
1990	-6.734
1991	49.788
1992	-38.644
1993	87.174
1994	49.258
1995	-7.136
1996	14.915
1997	-0.152
1998	5.715
1999	2.211
2000	4.582
2001	8.496
2002	6.217
2003	4.076
2004	-2.170
2005	17.581
2006	12.276
2007	8.228
2008	-7.950
2009	34.151
2010	21.024
2011	-6.733
2012	-12.466
2013	4.454
2014	33.158
2015	43.841
2016	-0.252
2017	-37.641
2018	-18.829
2019	-7.534
2020	-20.418
2021	-3.126
2022	36.654
2023	14.025
2024	6.547
2025	4.638
2026	2.447
2027	2.644
2028	3.590
2029	3.855