Year	%
1981	2.3
1988	2.7
1990	2.4
1992	2.2
1994	2.5
1996	2.6
1998	2.7
1999	2.5
2000	2.6
2002	2.6
2004	2.5
2006	2.5
2007	2.7
2008	2.7
2009	2.7
2010	2.7
2011	3
2012	2.8
2013	2.9
2014	3
2015	3.2
2016	3.1
2017	3.1
2018	3
2019	3.3
2020	3.2
2021	3.2