Year | Value | 2004 | 29.398559195544 | 2003 | 32.453357604109 | 2002 | 28.379667106533 | 2001 | 27.104783632835 | 2000 | 25.745014892961 | 1999 | 23.691505269793 | 1998 | 21.164681088985 | 1997 | 16.960582375044 | 1996 | 15.813102724714 | 1995 | 16.986451622554 | 1994 | 17.880002967421 | 1993 | 19.347414718969 | 1992 | 21.299820868786 | 1991 | 16.379558679495 | 1990 | 8.7273641851107 |
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