Year	Percent
1980	2.89
1981	3.013
1982	3.108
1983	3.251
1984	3.233
1985	3.286
1986	3.326
1987	3.329
1988	3.493
1989	3.569
1990	3.619
1991	3.572
1992	3.384
1993	3.477
1994	3.601
1995	3.737
1996	3.873
1997	3.87
1998	4.003
1999	4.196
2000	4.163
2001	4.266
2002	4.307
2003	4.467
2004	4.578
2005	4.774
2006	4.952
2007	5.158
2008	5.206
2009	5.671
2010	5.939
2011	6.083
2012	6.219
2013	6.4
2014	6.643
2015	6.943
2016	7.273
2017	7.516
2018	7.771
2019	8.073
2020	8.38
2021	8.717
2022	9.068
2023	9.432
2024	9.808