Year	Percent
1991	4.166
1992	3.765
1993	3.896
1994	3.968
1995	3.829
1996	3.548
1997	3.987
1998	3.869
1999	3.928
2000	3.912
2001	3.948
2002	3.978
2003	4.113
2004	4.228
2005	4.413
2006	4.215
2007	4.434
2008	4.215
2009	4.342
2010	4.447
2011	4.349
2012	4.321
2013	4.353
2014	4.521
2015	4.211
2016	4.25
2017	4.295
2018	4.307
2019	4.321
2020	4.338
2021	4.355
2022	4.376