Year	Percent change (Units)
1980	64.762
1981	41.940
1982	16.542
1983	23.309
1984	64.855
1985	112.710
1986	26.548
1987	86.771
1988	60.309
1989	80.788
1990	33.001
1991	57.599
1992	69.444
1993	48.227
1994	15.176
1995	45.133
1996	50.933
1997	49.065
1998	8.071
1999	-2.092
2000	8.610
2001	3.252
2002	3.302
2003	-3.474
2004	0.821
2005	3.358
2006	1.953
2007	4.627
2008	10.445
2009	-1.637
2010	1.071
2011	5.055
2012	2.061
2013	0.779
2014	-1.032
2015	1.481
2016	2.707
2017	-0.186
2018	0.381
2019	0.286
2020	1.463
2021	3.274
2022	7.917
2023	7.164
2024	3.000
2025	2.000
2026	2.000
2027	2.000
2028	2.000
2029	2.000