Year	% of total
1990	46.33128977633407
1991	49.32945590342605
1992	48.765778459864485
1993	49.72763479725323
1994	50.32334093717519
1995	50.848917495793984
1996	51.054428860219346
1997	49.94450960441965
1998	48.8809569143669
1999	48.19376604356892
2000	48.62595500146971
2001	49.64240000291536
2002	50.80628754289777
2003	52.88074708910748
2004	52.71814862866958
2005	53.50968930873071
2006	53.82799676987767
2007	53.924537356750186
2008	54.3371545098219