Year	% of total
1990	41.23561668133653
1991	41.4167085507508
1992	40.66040126592193
1993	37.73985110756087
1994	36.07031031020449
1995	34.47746224277743
1996	33.89788915394639
1997	33.89557972090059
1998	33.81226570905468
1999	33.610235671307905
2000	32.55537091814521
2001	31.035407250909017
2002	31.0796661424258
2003	31.03354250037187
2004	31.32527453683577
2005	31.206067585635104
2006	31.52486246110619
2007	32.24086463117662
2008	31.89250039414689