Year	% of total
1990	86.37649643247995
1991	86.24684801521191
1992	86.46889550342293
1993	86.34944126668852
1994	83.14748917960355
1995	83.20455334050288
1996	82.98876068000793
1997	82.46441403379372
1998	82.37360295881251
1999	82.20260535271356
2000	81.53981666049674
2001	81.40790651923727
2002	81.51342734372317
2003	81.47612142222906
2004	81.38189365663922
2005	81.41044685324167
2006	80.84057625149745
2007	80.95719305721691
2008	80.59755357122243