Year	%
1988	3.96
1989	3.76
1990	3.25
1991	3.21
1992	3.26
1993	3.32
1994	3.39
1995	2.89
1996	3.16
1997	2.55
1998	2.46
1999	2.34
2000	2.26
2001	2.45
2002	2.41
2003	2.33
2004	2.38
2005	2.36
2006	2.84
2007	2.77
2008	2.65
2009	2.62
2010	2.57
2011	2.44
2012	2.44
2013	1.88
2014	2.3
2015	2.15
2016	2.09
2017	2.08
2018	2.08
2019	1.28
2020	1.13
2021	1.09