Year	Percent change (Units)
1980	46.708
1981	1.391
1982	1.833
1983	1.833
1984	1.833
1985	1.833
1986	1.833
1987	1.833
1988	1.833
1989	1.833
1990	1.833
1991	85.265
1992	299.097
1993	1379.476
1994	949.771
1995	2672.230
1996	4146.010
1997	221.492
1998	107.429
1999	248.248
2000	325.029
2001	152.586
2002	108.893
2003	98.219
2004	43.525
2005	22.961
2006	13.305
2007	12.249
2008	12.465
2009	13.721
2010	14.480
2011	13.484
2012	10.285
2013	8.782
2014	7.298
2015	9.159
2016	30.694
2017	29.844
2018	19.629
2019	17.079
2020	22.277
2021	25.765
2022	21.360
2023	13.639
2024	22.004
2025	12.818
2026	8.506
2027	7.442
2028	7.442
2029	7.442