Year	% of total
1990	23.791174026583228
1991	23.07130073313267
1992	22.57889867087591
1993	22.932049012100524
1994	22.41352525291178
1995	22.38207436515882
1996	22.184083703540132
1997	21.569293382891757
1998	20.899258765384317
1999	20.767977517061933
2000	20.085977766509927
2001	20.041133920721105
2002	19.38385855634699
2003	19.59089067937624
2004	18.706906945284267
2005	18.681619529960976
2006	18.288727686492983
2007	17.948792127006794
2008	18.277017548195683