Year	% of total
1990	36.69961949583273
1991	38.82315941492357
1992	38.162243331850256
1993	38.4514178950286
1994	38.16212010102311
1995	39.24127824185871
1996	40.29881394746009
1997	40.26448419192746
1998	39.794371147666034
1999	39.31476534344602
2000	40.22441735000734
2001	40.30807331133239
2002	39.541571722487035
2003	39.91513567173319
2004	39.40405106037192
2005	39.193464324785644
2006	39.27297517913035
2007	38.94357729439183
2008	38.76734393694813