Year	Percent change (Units)
1980	47.059
1981	32.134
1982	123.555
1983	275.579
1984	1281.347
1985	11749.630
1986	273.350
1987	14.579
1988	16.002
1989	15.174
1990	17.120
1991	21.444
1992	12.958
1993	8.526
1994	7.875
1995	10.192
1996	12.430
1997	4.709
1998	7.674
1999	2.161
2000	4.601
2001	1.596
2002	0.923
2003	3.338
2004	4.437
2005	5.400
2006	4.300
2007	6.656
2008	14.007
2009	3.345
2010	2.502
2011	9.884
2012	4.517
2013	5.737
2014	5.765
2015	4.061
2016	3.625
2017	2.822
2018	2.272
2019	1.839
2020	0.942
2021	0.736
2022	1.747
2023	2.577
2024	4.484
2025	4.166
2026	3.869
2027	3.806
2028	3.803
2029	3.800