1993

7.7

1994

7.5

1999

6.4

2017

6.3

1999

7.1

2009

5.9

2002

5.9

1978

6.5

1972

6.6

1984

5.0

1968

4.9

2004

5.9

2005

6.2

1989

7.1

1975

6.8

2007

5.2

1995

6.1

1974

6.4

2001

6.1

1981

7.1