Year	Percent change (Units)
1980	3.409
1981	2.198
1982	7.296
1983	8.876
1984	8.021
1985	7.425
1986	4.759
1987	4.273
1988	3.994
1989	2.993
1990	2.350
1991	2.100
1992	0.300
1993	2.900
1994	4.188
1995	4.484
1996	4.879
1997	5.919
1998	7.543
1999	6.110
2000	5.383
2001	3.524
2002	3.186
2003	3.193
2004	4.092
2005	4.472
2006	6.844
2007	7.088
2008	7.156
2009	4.674
2010	5.147
2011	1.765
2012	2.226
2013	3.302
2014	2.930
2015	4.360
2016	4.340
2017	4.191
2018	5.327
2019	5.548
2020	3.573
2021	3.253
2022	6.653
2023	3.760
2024	2.966
2025	4.441
2026	4.732
2027	5.062
2028	5.486
2029	5.628