1989

6.3

1999

6.5

2005

4.8

1998

6.1

1976

8.1

1996

7.0

1973

6.0

2006

5.6

2017

4.0

2016

7.2

1976

6.6

2007

5.6

2019

6.0

2004

4.6

1998

6.3

1997

7.6

2002

6.4

2017

6.6

1999

5.5

2008

6.3