Year	Percent
1990	3.56189
1991	3.45562
1992	2.91861
1993	2.81206
1994	3.09223
1995	7.43061
1996	7.2418
1997	7.13418
1998	6.83867
1999	6.64986
2000	6.39193
2001	6.13291
2002	5.80306
2003	5.60888
2004	5.03339
2005	4.54866
2006	3.73522
2007	3.40324
2008	3.1125
2009	2.92783
2010	2.80905
2011	2.84049
2012	2.78378
2013	2.69248
2014	2.62048
2015	2.53199
2016	2.42629
2017	2.26924
2018	2.23014
2019	2.19691
2020	2.28539