Year	Percent change (Units)
1980	10.011
1981	8.903
1982	13.673
1983	8.972
1984	8.596
1985	7.551
1986	6.159
1987	8.224
1988	7.156
1989	7.722
1990	6.502
1991	7.693
1992	5.518
1993	4.040
1994	5.423
1995	6.232
1996	3.733
1997	3.599
1998	3.102
1999	2.768
2000	2.770
2001	1.945
2002	2.714
2003	2.720
2004	3.692
2005	1.962
2006	4.143
2007	3.421
2008	4.915
2009	3.541
2010	4.361
2011	3.240
2012	4.612
2013	5.316
2014	4.626
2015	4.437
2016	3.629
2017	5.309
2018	7.308
2019	6.722
2020	5.635
2021	5.707
2022	8.308
2023	9.323
2024	7.358
2025	6.943
2026	7.048
2027	7.917
2028	8.154
2029	8.978