Year	Percent
1991	2.56
1992	2.736
1993	2.584
1994	2.611
1995	2.723
1996	3.02
1997	2.972
1998	2.956
1999	3.215
2000	2.465
2001	2.612
2002	3.13
2003	3.339
2004	3.736
2005	4.19
2006	4.435
2007	5.14
2008	5.642
2009	6.09
2010	6.694
2011	6.701
2012	7.603
2013	7.24
2014	7.167
2015	7.16
2016	7.015
2017	7.057
2018	7.051
2019	7.103
2020	7.069
2021	7.042
2022	7.038