Year	%
1984	38.5
1987	36.9
1989	36.4
1992	37
1995	37.9
1997	38.4
2003	35.1
2006	33.8
2008	34.2
2011	33.2
2013	31.8
2015	31.3
2018	31.2
2021	30.9