1980

8.5

1989

5.9

2015

7.5

1990

5.8

2008

4.4

2014

5.7

1976

6.2

1992

6.8

2004

6.0

2002

9.0

1986

6.1

2020

6.1

2009

7.8

7.3

1951

7.0

1968

7.0