Year	% of total
1990	11.595071396381776
1991	11.747076841292134
1992	11.88978018229908
1993	11.99457670461118
1994	12.120057477822243
1995	12.040720694792133
1996	12.018465560128233
1997	12.03605646907937
1998	12.026766537681931
1999	11.997196164650234
2000	12.078841463892463
2001	12.494467363096994
2002	12.98075191375693
2003	13.243076188851319
2004	13.560208723804783
2005	13.706286366794895
2006	14.027171296158729
2007	14.298045310768268
2008	14.523745568476773