Year	Percent change (Units)
1980	26.189
1981	22.509
1982	19.048
1983	20.153
1984	18.050
1985	24.823
1986	17.001
1987	15.761
1988	13.969
1989	14.848
1990	22.883
1991	18.019
1992	14.402
1993	12.013
1994	10.666
1995	7.815
1996	6.950
1997	4.543
1998	3.696
1999	2.313
2000	3.669
2001	3.525
2002	3.498
2003	3.098
2004	3.129
2005	3.504
2006	3.199
2007	3.855
2008	2.193
2009	2.549
2010	5.158
2011	2.177
2012	0.318
2013	-1.816
2014	-2.535
2015	0.392
2016	0.290
2017	0.967
2018	0.632
2019	1.050
2020	-2.390
2021	4.359
2022	7.571
2023	3.688
2024	2.679
2025	2.043
2026	1.978
2027	1.920
2028	1.878
2029	1.900