Year	%
1991	20.1
1993	9.67
1996	7.75
1997	7.63
1998	6.99
1999	6.74
2000	6.55
2001	5.37
2002	5.1
2003	5.12
2004	5.19
2005	4.27
2006	3.83
2007	3.91
2008	4.06
2009	4.05
2010	2.85
2011	2.8
2012	2.76
2013	2.77
2014	2.84
2015	2.5
2016	2.3
2017	2.23
2018	2.22
2019	2.03
2020	1.97
2021	1.93