Year	Percent change (Units)
1980	17.986
1981	64.935
1982	82.677
1983	10.345
1984	17.578
1985	10.963
1986	15.269
1987	16.623
1988	25.167
1989	9.964
1990	27.346
1991	16.990
1992	16.969
1993	9.043
1994	19.856
1995	22.568
1996	13.889
1997	11.202
1998	12.356
1999	10.113
2000	10.247
2001	10.956
2002	9.683
2003	9.868
2004	13.129
2005	14.075
2006	9.434
2007	10.806
2008	13.902
2009	4.047
2010	5.824
2011	4.736
2012	4.551
2013	3.680
2014	5.127
2015	-0.808
2016	0.765
2017	2.574
2018	2.027
2019	1.522
2020	0.892
2021	3.299
2022	7.877
2023	-1.765
2024	1.992
2025	3.042
2026	3.000
2027	3.000
2028	3.000
2029	3.000