Year	Percent
1991	0.949
1992	0.612
1993	0.917
1994	1.328
1995	1.799
1996	2.028
1997	3.472
1998	3.412
1999	9.391
2000	8.74
2001	7.26
2002	7.103
2003	6.437
2004	6.673
2005	7.12
2006	6.723
2007	6.645
2008	6.604
2009	6.642
2010	5.958
2011	6.246
2012	6.035
2013	6.397
2014	6.254
2015	6.288
2016	6.388
2017	6.599
2018	6.586
2019	6.579
2020	6.577
2021	6.576
2022	6.574