Year	Percent change (Units)
1980	8.039
1981	3.327
1982	-4.009
1983	-9.640
1984	-18.757
1985	-16.518
1986	-3.809
1987	-4.276
1988	10.540
1989	21.861
1990	7.301
1991	4.618
1992	-12.984
1993	-15.712
1994	0.427
1995	41.596
1996	16.782
1997	-4.012
1998	4.875
1999	-7.318
2000	-9.582
2001	23.598
2002	10.364
2003	32.785
2004	5.077
2005	34.240
2006	-32.376
2007	1.157
2008	22.283
2009	0.749
2010	-11.249
2011	21.980
2012	15.291
2013	6.777
2014	4.877
2015	12.092
2016	-32.981
2017	-1.750
2018	8.587
2019	17.754
2020	-18.110
2021	-23.895
2022	8.000
2023	2.088
2024	3.199
2025	4.281
2026	1.695
2027	3.389
2028	3.167
2029	3.468