Year	Percent
1991	4.29644
1992	4.20156
1993	4.51039
1994	4.40838
1995	4.44653
1996	4.38631
1997	4.60308
1998	4.60866
1999	4.78286
2000	4.84899
2001	4.3502
2002	4.28561
2003	4.23623
2004	3.89447
2005	3.89896
2006	3.81191
2007	4.00312
2008	3.58799
2009	3.24895
2010	3.47018
2011	3.51365
2012	3.53053
2013	3.52774
2014	3.57784
2015	3.43879
2016	3.36249
2017	3.10872
2018	3.03022
2019	2.59134