Year	Percent change (Units)
1981	52.174
1982	40.714
1983	-11.094
1984	159.083
1985	39.220
1986	38.260
1987	106.470
1988	120.590
1989	56.120
1990	264.970
1991	4227.980
1992	2729.790
1993	4583.080
1994	9796.900
1995	370.272
1996	1705.110
1997	20.000
1998	133.333
1999	485.714
2000	509.756
2001	135.090
2002	15.751
2003	4.443
2004	9.217
2005	20.988
2006	18.196
2007	9.964
2008	27.572
2009	53.438
2010	9.838
2011	8.654
2012	2.769
2013	1.074
2014	1.030
2015	0.815
2016	11.236
2017	54.709
2018	7.228
2019	4.588
2020	15.756
2021	5.281
2022	13.132
2023	23.752
2024	11.696
2025	6.952
2026	6.952
2027	6.952
2028	6.952
2029	7.000