Year	Percent change (Units)
1980	-29.331
1981	8.216
1982	-25.206
1983	-13.157
1984	24.238
1985	20.773
1986	8.944
1987	7.734
1988	-0.176
1989	0.322
1990	10.243
1991	12.589
1992	9.924
1993	-0.728
1994	-0.645
1995	8.920
1996	7.940
1997	13.539
1998	0.000
1999	-10.650
2000	6.143
2001	-7.085
2002	10.405
2003	-0.638
2004	11.534
2005	11.764
2006	13.377
2007	18.098
2008	20.168
2009	-5.528
2010	8.836
2011	27.017
2012	8.536
2013	15.810
2014	11.894
2015	4.574
2016	-7.617
2017	4.732
2018	1.385
2019	0.221
2020	-26.641
2021	20.875
2022	21.318
2023	13.605
2024	2.521
2025	6.089
2026	2.270
2027	0.965
2028	2.427
2029	1.898