Year	Percent change (Units)
1980	13.727
1981	4.104
1982	18.788
1983	-6.318
1984	12.056
1985	4.170
1986	15.051
1987	21.108
1988	26.114
1989	21.145
1990	11.686
1991	17.280
1992	13.807
1993	12.735
1994	14.245
1995	15.445
1996	-5.525
1997	7.234
1998	8.242
1999	9.031
2000	17.488
2001	-4.211
2002	5.887
2003	9.134
2004	14.631
2005	7.760
2006	10.788
2007	8.894
2008	6.264
2009	-12.140
2010	14.220
2011	9.509
2012	3.662
2013	2.514
2014	0.345
2015	1.250
2016	2.696
2017	5.181
2018	3.351
2019	-2.954
2020	-19.681
2021	11.089
2022	6.142
2023	2.612
2024	4.932
2025	4.536
2026	3.343
2027	3.894
2028	3.648
2029	3.639