Year	Percent change (Units)
1980	22.587
1981	-6.128
1982	11.585
1983	27.321
1984	21.856
1985	-3.246
1986	9.683
1987	-3.749
1988	-2.289
1989	18.441
1990	1.512
1991	13.114
1992	7.006
1993	8.955
1994	-6.383
1995	10.626
1996	4.260
1997	38.936
1998	1.265
1999	23.553
2000	-3.385
2001	23.990
2002	33.012
2003	-11.849
2004	-5.322
2005	16.796
2006	-1.750
2007	-6.056
2008	-4.709
2009	-12.580
2010	-1.017
2011	7.407
2012	8.999
2013	10.204
2014	-1.831
2015	31.202
2016	-3.903
2017	13.567
2018	-2.601
2019	7.651
2020	-21.883
2021	5.392
2022	8.217
2023	2.395
2024	2.213
2025	4.052
2026	2.904
2027	3.911
2028	3.634
2029	3.690