Year	%
1990	32.9474738863206
1991	32.3141346133937
1992	31.7209674909553
1993	31.1647261293037
1994	30.6924524168107
1995	30.2238411714082
1996	29.7945506445119
1997	29.3730667025853
1998	28.9797292757304
1999	28.5905878431253
2000	28.2095840817134
2001	27.8728107533781
2002	27.6239137318611
2003	27.3928280075592
2004	27.1425847248582
2005	26.889353023105
2006	26.6594973568129
2007	26.3874193449258
2008	26.1533899364257
2009	26.0036745450557
2010	25.9134584788342
2011	25.8880107753511
2012	25.96507528871
2013	26.0319943389802
2014	26.1661967310935
2015	26.4242171528669
2016	26.7944106347259