Year	Percent change (Units)
1980	90.227
1981	101.737
1982	100.574
1983	135.020
1984	192.121
1985	226.029
1986	147.137
1987	228.327
1988	629.118
1989	1430.724
1990	2947.733
1991	432.772
1992	951.956
1993	1927.381
1994	2075.827
1995	66.008
1996	15.757
1997	6.926
1998	3.196
1999	4.859
2000	7.044
2001	6.840
2002	8.450
2003	14.714
2004	6.598
2005	6.870
2006	4.184
2007	3.641
2008	5.678
2009	4.888
2010	5.039
2011	6.636
2012	5.404
2013	6.204
2014	6.329
2015	9.030
2016	8.740
2017	3.446
2018	3.665
2019	3.733
2020	3.212
2021	8.302
2022	9.280
2023	4.594
2024	4.113
2025	3.039
2026	3.050
2027	2.967
2028	3.015
2029	2.991