1981

7.1

2002

4.5

1999

6.8

2002

6.3

1990

6.5

1998

5.6

2003

5.7

2004

6.6

2001

5.9

1989

7.4

1992

5.2

1991

6.2

1990

6.7

2002

6.3

2015

5.8

1962

6.9

2008

6.2

2011

7.0

1997

7.6

2004

6.5