1986

6.5

2000

5.7

1979

4.8

2003

5.6

2006

5.1

1990

6.7

2014

6.3

2020

5.0

1990

2.5

2003

6.2

2002

6.6

2001

7.2

1997

7.4

1994

7.1

1954

7.9

1997

5.8

1999

8.5

2003

7.2

1989

6.3

1975

8.4