Year	% of total
1990	51.399365764919615
1991	50.266568669522584
1992	49.113438044268435
1993	48.49385525082952
1994	46.57572239948138
1995	46.48026177691491
1996	46.46012964739086
1997	46.09660630849017
1998	46.15509623753642
1999	47.005729327946504
2000	47.82392937038968
2001	48.6656856676472
2002	48.934746094099765
2003	50.68707872410961
2004	51.47540052379167
2005	52.047600319917684
2006	52.30364500368516
2007	52.777021222613996
2008	53.10911505410153