1977

7.3

1997

5.8

2004

6.4

2007

5.4

2007

4.5

2004

6.6

1996

6.3

1991

7.1

1986

6.3

2002

6.5

1979

6.3

1981

6.1

1982

6.1

1987

5.7

1981

6.4

2007

5.9

2016

6.3

1994

5.8

2003

6.1

2005

6.3