Year	Percent change (Units)
1981	1.615
1982	-3.775
1983	0.851
1984	1.085
1985	7.828
1986	2.666
1987	2.914
1988	0.466
1989	1.830
1990	-4.256
1991	-6.096
1992	0.247
1993	20.244
1994	8.844
1995	15.591
1996	9.396
1997	23.093
1998	23.784
1999	13.305
2000	20.294
2001	5.306
2002	6.780
2003	9.288
2004	17.284
2005	10.345
2006	12.891
2007	13.905
2008	5.893
2009	-14.187
2010	9.745
2011	4.054
2012	-3.141
2013	4.116
2014	10.901
2015	5.677
2016	3.471
2017	8.397
2018	6.964
2019	8.206
2020	-3.855
2021	7.334
2022	17.617
2023	-3.956
2024	4.500
2025	5.750
2026	5.673
2027	5.579
2028	5.817
2029	5.598