Year	Percent
1991	5.902
1992	6.546
1993	6.365
1994	7.506
1995	7.541
1996	7.222
1997	7.011
1998	6.918
1999	7.62
2000	7.947
2001	8.563
2002	8.48
2003	9.567
2004	12.178
2005	12.674
2006	12.643
2007	12.952
2008	13.806
2009	15.688
2010	15.984
2011	15.933
2012	15.462
2013	15.549
2014	15.397
2015	15.162
2016	15.431
2017	15.354
2018	15.402
2019	15.425
2020	15.372
2021	15.355
2022	15.351