Year	% of total
1990	57.70960449908774
1991	56.90001464531836
1992	56.214770511505584
1993	55.32764484524386
1994	54.92501371505912
1995	55.76248224130103
1996	55.906553405991126
1997	56.78633833987607
1998	58.71002080571329
1999	59.52549238044544
2000	60.12324343001884
2001	59.082076959391784
2002	59.29556543062729
2003	58.661609799717745
2004	57.99875064233383
2005	58.29401705447448
2006	57.530189919702565
2007	58.108001280839964
2008	58.13819700041078