A Survey of Open Space

5.2

/

1989

7.107

/

2006

6.6

/

2009

7.45

/

2019

6.157

/

2003

7.1

/

2009

7.5

/

2010

5.6

/

2014

7.6

/

2013

6.105

/

NaN

6.5

/

2012

7.17

/

2021

6.2

/

1989

6.481

/

1990

6.9

/

1957

5.8

/

1998

7.8

/

2010

6.09

/

2013

5.7

/

2021

6.447

/

2008