Year	Percent change (Units)
1980	26.145
1981	17.969
1982	10.826
1983	13.964
1984	16.638
1985	1.481
1986	7.976
1987	7.717
1988	13.992
1989	11.568
1990	21.495
1991	12.186
1992	11.383
1993	11.747
1994	8.448
1995	7.675
1996	15.937
1997	9.565
1998	9.371
1999	4.692
2000	6.176
2001	14.158
2002	9.551
2003	8.969
2004	9.014
2005	11.009
2006	9.939
2007	15.895
2008	22.356
2009	3.503
2010	6.214
2011	6.730
2012	7.547
2013	6.884
2014	2.784
2015	2.224
2016	3.985
2017	6.580
2018	4.273
2019	4.304
2020	4.569
2021	5.954
2022	45.214