Year % of total 1990 7.149970850126812 1991 7.294854572455584 1992 7.234468932727589 1993 7.341329666785672 1994 7.010793891775752 1995 6.83457936106441 1996 6.88061993415216 1997 7.0157798261065105 1998 6.908327331882247 1999 6.859080707542042 2000 7.095656239909544 2001 7.130389752998693 2002 6.981151280979011 2003 7.018374036331171 2004 6.976537589771237 2005 6.962636357702125 2006 7.085074191521721 2007 7.1130133088086085 2008 7.2226058448407455