Year	Percent change (Units)
1980	-5.025
1981	-5.379
1982	4.444
1983	10.479
1984	0.000
1986	6.859
1987	6.428
1988	-11.820
1989	16.105
1990	-17.648
1991	-20.742
1992	-31.421
1993	-29.029
1994	5.572
1995	39.585
1996	-0.470
1997	-23.554
1998	27.795
1999	-45.127
2000	32.457
2001	20.026
2002	34.104
2003	11.250
2004	28.933
2005	41.120
2006	0.184
2007	68.855
2008	13.236
2009	-17.890
2010	48.027
2011	-1.284
2012	-2.907
2013	27.403
2014	19.994
2015	-4.393
2016	20.447
2017	-10.520
2018	27.042
2019	-13.152
2020	-7.097
2021	33.793
2022	31.847
2023	0.142
2024	4.036
2025	4.824
2026	3.449
2027	3.247
2028	3.047
2029	2.684