1999

8.1

2020

6.5

1992

6.8

2000

6.2

1993

8.0

2004

8.3

2004

8.6

1990

8.6

2003

7.6

1977

7.3

2006

7.5

2004

7.4

2003

6.7

2005

4.5

1986

3.0

1987

7.7

2014

7.9

2013

8.5

1984

6.5

2016

6.0