1987

4.0

1992

5.7

2001

6.1

1996

6.2

2012

7.7

2015

5.0

2014

4.6

2000

6.0

2013

6.2

1959

6.9

2009

6.5

1989

7.8

1998

7.5

1994

8.3

2007

6.1

2007

6.3

1987

7.1

2014

6.7

2001

5.8

2007

6.2