Year	% of total
1990	11.923023327727188
1991	12.295720882607146
1992	12.759872084104218
1993	13.097273315373448
1994	13.27109042188923
1995	13.682442272536509
1996	13.824976968383252
1997	14.224164091834849
1998	14.678067400434767
1999	14.705469720397565
2000	14.64922005282994
2001	14.402742145400396
2002	14.522656941724716
2003	15.114784355001516
2004	14.487347736193117
2005	14.779507209108079
2006	14.301385476823812
2007	13.992097668088405
2008	14.543860602488307