Year	% of total
1990	42.35819549100649
1991	40.71975787403467
1992	39.18830329562523
1993	37.042796207715014
1994	36.215876463390856
1995	36.1696602009398
1996	35.08480789297411
1997	32.246960049303816
1998	31.129887209956767
1999	31.03642423027648
2000	30.317549791263243
2001	29.556999844004768
2002	28.672915628768656
2003	23.288000589134825
2004	22.8405754758016
2005	23.05753717210706
2006	24.268621559860165
2007	21.99722353520874
2008	24.95570528790264