Year	Percent change (Units)
1980	25.486
1981	3.412
1982	1.205
1983	6.947
1984	17.199
1985	-1.179
1986	12.008
1987	15.053
1988	31.266
1989	7.358
1990	10.669
1991	9.542
1992	5.788
1993	17.753
1994	19.215
1995	26.744
1996	9.692
1997	10.884
1998	-4.867
1999	8.205
2000	16.335
2001	-5.163
2002	6.564
2003	15.236
2004	18.428
2005	13.061
2006	9.160
2007	6.066
2008	3.940
2009	-9.240
2010	18.877
2011	7.887
2012	-0.274
2013	4.266
2014	1.214
2015	1.532
2016	-1.415
2017	6.806
2018	4.350
2019	-1.975
2020	2.082
2021	9.419
2022	5.053
2023	-3.411
2024	0.961
2025	4.424
2026	3.525
2027	3.387
2028	2.377
2029	2.340