Year	Percent change (Units)
1980	-5.096
1981	14.092
1982	34.189
1983	7.968
1984	-6.027
1985	-16.597
1986	17.455
1987	-12.749
1988	6.341
1989	13.549
1990	5.911
1991	6.200
1992	-4.824
1993	-6.047
1994	3.746
1995	25.939
1996	-2.660
1997	-16.416
1998	16.020
1999	4.896
2000	-28.543
2001	5.327
2002	7.419
2003	19.072
2004	13.334
2005	-2.702
2006	-22.041
2007	14.047
2008	-5.131
2009	25.483
2010	-3.606
2011	17.429
2012	0.839
2013	14.428
2014	6.797
2015	-1.423
2016	6.107
2017	13.259
2018	12.529
2019	13.241
2020	-3.023
2021	20.715
2022	-4.032
2023	1.415
2024	20.031
2025	22.158
2026	7.888
2027	7.491
2028	8.112
2029	6.896