Year	%
1980	13.2
1985	11.9
1990	11.2
1993	14.2
1994	15
1995	14
1996	15.5
1997	14
1998	14.5
1999	12.5
2000	13.2
2003	13.2
2004	13.1
2005	13
2006	14
2007	13.9
2008	14.8
2009	15
2010	14.7
2011	15.8
2012	15.9
2013	17.8
2014	17.3
2015	17.4
2016	16.9
2017	16.1
2018	15.7
2019	15.9
2020	16.5
2021	15.4