Year	Percent change (Units)
1980	23.900
1981	19.300
1982	18.600
1983	7.200
1984	17.600
1985	69.400
1986	95.400
1987	487.200
1988	155.000
1989	72.200
1990	68.900
1991	50.115
1992	99.847
1993	24.737
1994	8.235
1995	10.282
1996	8.879
1997	7.748
1998	4.549
1999	0.241
2000	-0.356
2001	-0.367
2002	1.759
2003	1.268
2004	1.672
2005	-1.426
2006	4.092
2007	4.058
2008	10.698
2009	1.215
2010	3.962
2011	4.986
2012	6.573
2013	5.559
2014	1.128
2015	-3.761
2016	-0.807
2017	4.485
2018	6.058
2019	2.891
2020	84.880
2021	154.759
2022	171.195