Year	Percent change (Units)
1981	25.370
1982	44.710
1983	83.127
1984	52.279
1985	74.527
1986	116.347
1987	116.797
1988	38.328
1989	85.543
1990	98.286
1991	115.377
1992	34.799
1993	26.690
1994	17.730
1995	34.527
1996	6.379
1997	66.923
1998	-5.677
1999	36.745
2000	-3.052
2001	3.432
2002	-3.080
2003	11.286
2004	14.391
2005	13.100
2006	8.263
2007	13.763
2008	9.290
2009	7.532
2010	7.405
2011	6.646
2012	6.203
2013	5.374
2014	4.606
2015	8.383
2016	17.420
2017	15.324
2018	14.237
2019	13.902
2020	10.447
2021	17.938
2022	37.090
2023	52.156
2024	26.080
2025	17.400
2026	12.900
2027	9.800
2028	8.000
2029	7.000