1991

7.3

2005

6.4

1997

8.4

2007

6.4

2006

6.5

2001

6.3

1960

7.7

1996

5.2

2002

6.2

2007

7.6

2001

5.3

1950

6.8

1968

6.8

1995

7.6

1996

6.2

1967

6.5

1993

6.1

2013

7.3

2018

3.0

1991

6.5