Year	% of total
1990	57.709604499087746
1991	56.90001464531837
1992	56.21477051150561
1993	55.32764484524385
1994	54.925013715059116
1995	55.76248224130102
1996	55.90655340599109
1997	56.78633833987607
1998	58.710020805713306
1999	59.52549238044546
2000	60.123243430018825
2001	59.082076959391784
2002	59.295565430627306
2003	58.66160979971775
2004	57.99875064233383
2005	58.294017054474494
2006	57.530189919702565
2007	58.108001280839964
2008	58.13819700041075