Year	%
1987	20.8
1990	20.3
1992	18.7
1994	20.3
1996	19.6
1998	20.5
2000	19.3
2003	19.5
2006	17.1
2009	15.8
2011	15
2013	14.5
2015	14.5
2017	14
2020	13.4
2022	13.8