Year	Percent change (Units)
1981	-28.960
1982	-30.085
1983	3.933
1984	6.591
1985	10.068
1986	31.207
1987	14.740
1988	-41.031
1989	27.537
1990	59.698
1991	9.975
1992	-8.101
1993	-5.785
1994	23.158
1995	-24.138
1996	-7.770
1997	-23.055
1998	-6.739
1999	-34.796
2000	123.353
2001	20.179
2002	37.519
2003	17.977
2004	-14.122
2005	1.241
2006	7.067
2007	-5.081
2008	-10.952
2009	40.397
2010	13.542
2011	3.807
2012	115.661
2013	52.315
2014	3.210
2015	-23.196
2016	-1.066
2017	-9.901
2018	-4.428
2019	-2.847
2020	-12.531
2021	75.606
2022	4.601
2023	25.541
2024	12.253
2025	1.915
2026	4.371
2027	4.825
2028	1.209
2029	6.252