Year	% of total
1990	3.5543911247149413
1991	4.027384342112248
1992	4.040370143279089
1993	4.071644736981254
1994	4.0793372712785665
1995	3.799882454996655
1996	4.223834314438665
1997	4.263362637310471
1998	4.172043092662276
1999	4.223979026583703
2000	4.280331167753278
2001	4.155257733177036
2002	4.125879502337106
2003	4.092593494869967
2004	4.084992763413393
2005	4.272863666882611
2006	4.431742986241781
2007	4.4656895103227345
2008	4.728359848586144