Year	Percent change (Units)
1980	-43.979
1981	10.362
1982	-15.937
1983	19.713
1984	-13.532
1985	-22.934
1986	-16.847
1987	7.668
1988	-17.743
1989	24.244
1990	13.129
1991	-11.121
1992	-23.139
1993	22.832
1994	-23.100
1995	26.913
1996	9.651
1997	17.695
1998	0.815
1999	14.102
2000	13.593
2001	5.104
2002	-6.386
2003	5.174
2004	19.530
2005	4.477
2006	74.561
2007	10.709
2008	2.082
2009	2.347
2010	17.378
2011	6.152
2012	13.920
2013	5.255
2014	6.320
2015	-3.289
2016	1.633
2017	8.108
2018	1.247
2019	1.851
2020	-2.512
2021	16.236
2022	-0.994
2023	-1.440
2024	4.169
2025	3.740
2026	4.234
2027	4.595
2028	5.617
2029	5.829