Year	Percent change (Units)
1980	5.299
1981	13.279
1982	-14.482
1983	9.233
1984	4.041
1985	-8.984
1986	50.122
1987	14.018
1988	21.488
1989	31.890
1990	-13.070
1991	-7.661
1992	-9.761
1993	-10.428
1994	-11.008
1995	-5.898
1996	-3.065
1997	32.336
1998	11.545
1999	-6.099
2000	-8.063
2001	-2.805
2002	3.218
2003	-6.586
2004	19.318
2005	-6.275
2006	-1.442
2007	36.396
2008	63.908
2009	-13.487
2010	8.695
2011	11.526
2012	28.350
2013	14.484
2014	-3.763
2015	7.116
2016	-23.289
2017	-15.802
2018	17.596
2019	11.439
2020	15.377
2021	2.189
2022	-14.557
2023	-13.638
2024	10.025
2025	7.823
2026	12.214
2027	6.186
2028	5.843
2029	5.858