1964

7.1

1970

7.2

2003

5.4

2002

6.8

2005

5.3

2003

5.9

2009

6.6

1997

5.9

1988

6.3

2017

6.9

2014

6.7

2001

7.3

1996

6.4

2007

3.3

2007

5.0

1994

7.5

1980

6.6

2010

4.2

2020

5.6

2005

5.5