JFK flights usually have the highest load factor in F.
Could also be an indicator that activity is slowing and Japanese companies aren't shuffling their C-levels in F right now. In 2009-2010, F was frequently empty on NH 5/6, and the flight attendants would keep the curtains between C (then rows 3 and 5) and F open. Of course, nobody was allowed to sit up front, but it was a unique sight!