Year	Percent change (Units)
1980	11.400
1981	13.299
1982	-1.295
1983	15.227
1984	14.142
1985	-0.602
1986	37.600
1987	25.862
1988	11.633
1989	-4.134
1990	4.369
1991	13.669
1992	11.895
1993	8.818
1994	17.567
1995	22.713
1996	8.922
1997	19.091
1998	16.239
1999	15.513
2000	18.906
2001	-1.900
2002	15.748
2003	16.170
2004	20.673
2005	9.240
2006	13.291
2007	12.301
2008	6.040
2009	0.208
2010	13.803
2011	17.225
2012	5.026
2013	3.919
2014	1.117
2015	-0.303
2016	1.982
2017	4.408
2018	3.267
2019	-1.072
2020	-0.168
2021	10.667
2022	3.600
2023	3.054
2024	3.236
2025	3.076
2026	3.266
2027	3.229
2028	3.066
2029	3.023