Year	%
1988	4.55
1989	4.41
1990	4
1991	3.97
1992	3.97
1993	4.03
1994	4.12
1995	4.04
1996	4.25
1997	4.01
1998	3.89
1999	3.88
2000	4.25
2001	4.43
2002	4.41
2003	4.25
2004	4.17
2005	4.05
2006	4.35
2007	4.11
2008	3.92
2009	3.93
2010	3.63
2011	3.84
2012	3.8
2013	2.33
2014	3.77
2015	3.52
2016	3.51
2017	3.69
2018	3.77
2019	5.91
2020	2.31
2021	2.18