1997

6.3

2011

7.2

6.1

2009

8.5

5.6

2010

9.1

2007

9.8

2015

6.5

2021

5.6

1943

6.6

1974

10.0

1975

4.0

1912

4.7

2013

3.0

1994

9.7

1934

6.9