Year	%
1988	15.35
1991	11.06
1993	9.37
1996	6.43
1997	5.21
1998	5
1999	4.89
2000	4.64
2001	4.72
2002	4.59
2003	4.45
2004	4.99
2005	4.79
2006	3.71
2007	3.39
2008	3.61
2009	3.17
2010	2.99
2011	4.4
2012	4.67
2013	4.48
2014	1.55
2016	4.28
2020	3.85
2021	3.88