1983

6.4

1999

5.3

1989

5.8

2014

5.0

1971

8.2

1984

7.7

2009

6.1

1991

8.1

1995

7.0

2003

6.2

1972

6.4

1983

7.3

1984

6.2

1990

7.3

1987

6.5

2001

5.8

1997

7.6

1999

7.4

2002

6.6

2004

6.4