1999

6.8

1997

6.6

1998

6.6

1993

5.5

1994

7.0

2005

6.7

2006

7.1

1999

7.7

2003

7.2

2001

6.7

2006

6.2

2014

5.1

1991

5.7

2005

4.9

1978

4.9

1998

5.9

1974

4.7

1990

4.4

1970

2.5

1976

3.7