1977

0.0

1988

5.9

2007

6.9

1995

7.3

2000

7.1

1977

7.4

2001

6.8

1995

7.3

1991

6.0

2006

5.1

2003

6.6

2002

6.1

1998

0.0

2001

6.9

1970

7.2

2009

6.7

2011

8.2

1937

5.8

1919

6.3

2017

4.5