Year	Percent
1991	2.437
1992	2.319
1993	2.417
1994	2.697
1995	2.881
1996	2.952
1997	3.033
1998	2.959
1999	2.944
2000	2.874
2001	2.811
2002	2.754
2003	2.797
2004	2.917
2005	2.973
2006	2.984
2007	3.111
2008	3.251
2009	3.298
2010	3.441
2011	3.455
2012	3.488
2013	3.543
2014	3.612
2015	3.634
2016	3.68
2017	3.655
2018	3.699
2019	3.746
2020	3.806
2021	3.867
2022	3.928