Year	Percent
1991	3.532
1992	3.369
1993	3.316
1994	3.483
1995	3.501
1996	3.347
1997	3.407
1998	3.437
1999	3.6
2000	3.498
2001	3.508
2002	3.539
2003	3.294
2004	3.414
2005	3.433
2006	3.466
2007	3.538
2008	3.518
2009	3.569
2010	3.617
2011	3.61
2012	3.759
2013	2.99
2014	3.178
2015	3.234
2016	3.305
2017	3.281
2018	3.354
2019	3.428
2020	3.508
2021	3.59
2022	3.67