Gray!! Sorry, couldn't resist.
There are as many shades of gray as there are clouds in the sky, so I don't know for sure. This link: http://www.ipmsstockholm.org/colorcharts/stuff_eng_colorcharts_fs.htm
shows all of the "FS" gray shades (the grays are about halfway down the page) and you may be able to find it there.
Someone else may know the exact color that is being used, but this is as close as I can get you.