Year	% of total
1990	65.47409625552467
1991	64.31426416246637
1992	63.7378342448678
1993	63.11765067818741
1994	61.648202199471285
1995	61.98124606626176
1996	62.637609328019465
1997	63.115025978283974
1998	63.71206433050622
1999	64.88597904089264
2000	66.177330709942
2001	67.35358993199434
2002	67.48845414980877
2003	69.07452752035103
2004	70.01294446265818
2005	70.32946297047091
2006	70.50587598108372
2007	70.7165311234135
2008	70.5616775016275