Year	Percent
1991	8.306
1992	7.72
1993	7.036
1994	6.934
1995	6.675
1996	6.419
1997	6.243
1998	6.162
1999	5.936
2000	5.742
2001	5.712
2002	5.532
2003	5.341
2004	4.761
2005	4.798
2006	4.889
2007	4.562
2008	4.276
2009	4.379
2010	4.482
2011	4.397
2012	4.475
2013	4.431
2014	4.524
2015	4.683
2016	4.857
2017	4.898
2018	4.839
2019	4.787
2020	4.734
2021	4.688
2022	4.645