Year	Percent (Units)
1980	3.022
1981	3.137
1982	3.234
1983	3.388
1984	3.368
1985	3.423
1986	3.466
1987	3.472
1988	3.641
1989	3.721
1990	3.775
1991	3.724
1992	3.536
1993	3.633
1994	3.764
1995	3.905
1996	4.044
1997	4.044
1998	4.178
1999	4.394
2000	4.354
2001	4.456
2002	4.499
2003	4.664
2004	4.780
2005	4.928
2006	5.060
2007	5.174
2008	5.182
2009	5.614
2010	5.787
2011	5.862
2012	6.097
2013	6.116
2014	6.171
2015	6.382
2016	6.640
2017	6.746
2018	6.934
2019	7.009
2020	6.801
2021	7.011
2022	7.257
2023	7.590
2024	7.860
2025	8.108
2026	8.370
2027	8.644
2028	8.931
2029	9.230