Year	Percent change (Units)
1981	95.655
1982	104.804
1983	164.000
1984	215.279
1985	242.248
1986	79.656
1987	363.414
1988	980.221
1989	1972.912
1990	1620.966
1991	472.685
1992	1119.092
1993	2477.148
1994	916.433
1995	22.409
1996	9.564
1997	5.225
1998	1.656
1999	8.940
2000	5.974
2001	7.673
2002	12.530
2003	9.300
2004	7.601
2005	5.690
2006	3.142
2007	4.457
2008	5.902
2009	4.312
2010	5.909
2011	6.503
2012	5.839
2013	5.911
2014	6.408
2015	10.673
2016	6.288
2017	2.947
2018	3.745
2019	4.306
2020	4.517
2021	10.061
2022	5.785
2023	4.621
2024	3.796
2025	3.001
2026	3.002
2027	2.998
2028	3.000
2029	3.000