1971

6.7

2004

6.1

2013

4.6

2001

7.0

1986

7.2

2013

6.1

2021

7.0

2017

6.9

2011

5.6

1969

7.6

1987

7.0

1952

6.2

2008

6.3

1989

7.3

1992

5.4

1999

6.5

2013

7.7

2015

5.2

2020

5.7

2014

6.1