Year	Percent change (Units)
1980	19.199
1981	-0.798
1982	11.153
1983	10.014
1984	-3.819
1985	-0.496
1986	32.918
1987	12.383
1988	-4.674
1989	13.835
1990	10.100
1991	18.050
1992	14.689
1993	7.752
1994	-8.846
1995	4.179
1996	1.823
1997	-1.262
1998	8.080
1999	-1.320
2000	12.164
2001	12.625
2002	14.906
2003	14.235
2004	-5.273
2005	15.936
2006	7.595
2007	1.272
2008	-3.258
2009	-2.208
2010	5.792
2011	4.849
2012	-5.881
2013	16.260
2014	0.366
2015	8.138
2016	-5.810
2017	-1.683
2018	5.963
2019	-1.301
2020	-2.786
2021	3.644
2022	6.025
2023	-7.635
2024	18.538
2025	5.247
2026	7.460
2027	6.060
2028	5.277
2029	5.495