Year	% of total
1990	78.76481574099286
1991	78.7137816341921
1992	78.7161079130238
1993	78.55504466742372
1994	76.35698845277247
1995	76.27296137224441
1996	75.93925046966878
1997	75.7905823573444
1998	76.76855732907438
1999	77.76872231170584
2000	77.17615681396491
2001	77.43172357546452
2002	77.71579516277757
2003	77.32673214490173
2004	77.48159187384401
2005	77.40628946003835
2006	77.54378347404489
2007	77.98605762750498
2008	78.20513404991335