Year	Percent change (Units)
1981	16.700
1982	38.256
1983	60.058
1984	59.518
1985	83.999
1986	-17.640
1987	-13.174
1988	2.524
1989	6.064
1990	0.922
1991	-3.425
1992	-4.279
1993	5.452
1994	31.841
1995	19.872
1996	4.541
1997	3.017
1998	7.936
1999	0.372
2000	4.836
2001	8.739
2002	7.582
2003	7.324
2004	4.237
2005	5.637
2006	4.465
2007	2.798
2008	4.652
2009	5.737
2010	5.320
2011	4.799
2012	3.442
2013	3.179
2014	4.296
2015	1.695
2016	1.398
2017	0.746
2018	1.346
2019	1.244
2020	4.766
2021	-0.094
2022	4.869
2023	2.499
2024	4.400
2025	1.763
2026	2.557
2027	2.220
2028	2.017
2029	1.546