Year	% of total
1990	71.12006317307362
1991	72.72748418310383
1992	72.3086782505653
1993	71.43226073033418
1994	70.93693992198443
1995	72.03012256041762
1996	72.20942443849724
1997	72.02884615384615
1998	72.0256384169295
1999	72.04724409448819
2000	69.4509391317902
2001	70.88133387269818
2002	68.82006101950567
2003	71.75492437290578
2004	75.5216969153783
2005	73.85293380694799
2006	68.81811965334859
2007	73.40661636074049
2008	76.66289043534552
2009	73.80256638292467
2010	80.65363114972291
2011	81.09856096828587
2012	74.79341068985207
2013	75.19449779795511
2014	71.9476910191495
2015	71.56892211744373