1897

3.7

2000

4.1

2007

5.2

1998

5.0

1988

6.8

2006

6.8

2023

6.3

1999

5.8

1971

7.2

2005

6.7

2006

6.5

1996

7.0

2013

5.4

2018

6.2

1987

5.0

2005

5.8

2001

6.2

2005

6.1

2005

5.7

1989

6.9