Year	%
1988	18.56
1989	18.63
1990	14.04
1992	13.85
1993	16.46
1994	15.94
1995	15.94
1996	14.44
1997	9.81
1998	8.23
1999	7.72
2000	6.03
2001	5.89
2002	6.03
2003	4.97
2004	5.26
2005	6.33
2006	6.31
2007	5.17
2008	4.72
2009	4.67
2010	4.62
2011	2.49
2012	2.43
2013	2.45
2015	2.3
2016	4.64
2017	2.33
2018	4.54
2019	4
2020	4.04
2021	4.52