Year	% of total
1990	20.450694131090085
1991	20.899840588955286
1992	21.53581275721911
1993	21.928360084928297
1994	22.046409336974456
1995	22.35350869098256
1996	22.26949093251976
1997	23.230622377376694
1998	23.97469391510692
1999	23.98710504158544
2000	24.32134123168828
2001	24.09179389261191
2002	23.77352831303119
2003	22.98865648050162
2004	22.477774337729343
2005	21.756540260232708
2006	20.96944914914414
2007	19.265574885324323
2008	19.289839458859586