Year	Percent change (Units)
1980	-43.145
1981	-22.534
1982	5.512
1983	46.461
1984	21.977
1985	13.196
1986	29.093
1987	18.607
1988	2.457
1989	-28.041
1990	32.598
1991	32.633
1992	51.364
1993	22.835
1994	26.915
1995	13.473
1996	36.174
1997	24.432
1998	-4.046
1999	14.787
2000	-1.856
2001	4.007
2002	11.173
2003	20.609
2004	31.446
2005	7.575
2006	14.366
2007	13.700
2008	3.216
2009	6.471
2010	6.356
2011	9.827
2012	15.030
2013	18.408
2014	12.294
2015	15.278
2016	11.799
2017	17.823
2018	12.075
2019	4.766
2020	7.648
2021	14.892
2022	4.386
2023	-5.661
2024	4.679
2025	5.513
2026	7.217
2027	7.179
2028	6.937
2029	6.964