Year	Percent
1988	1.76
1991	3.15
1992	3.24
1993	3.37
1994	4.44
1995	7.1
1996	5.47
1997	4.24
1998	3.73
1999	2.6
2000	2.65
2001	2.63
2002	3
2003	3.46
2004	3.94
2005	3.56
2006	3.57
2007	3.63
2008	3.87
2009	5.36
2010	5.3
2011	5.17
2012	4.89
2013	4.91
2014	4.81
2015	4.31
2016	3.86
2017	3.42
2018	3.28
2019	3.48
2020	4.45