Year	Percent
1991	1.882
1992	1.892
1993	1.954
1994	2.026
1995	2.171
1996	2.176
1997	1.912
1998	2.003
1999	2.157
2000	2.463
2001	3.027
2002	3.013
2003	3.112
2004	3.201
2005	3.517
2006	3.914
2007	5.152
2008	4.346
2009	6.727
2010	5.235
2011	4.114
2012	4.327
2013	4.453
2014	5.209
2015	6.019
2016	6.601
2017	6.797
2018	6.686
2019	6.699
2020	6.653
2021	6.599
2022	6.588