The question: "When will the Arctic be ice free?" can be posed differently as: "When will we have 100% ice loss during the melting season?". The interactive chart above tries to answer second question. The yearly loss is defined as the difference between maximum and minimum volume.
'Ice free' and 'ice loss' are slightly different concepts or metaphors. A loss of 100% means the Arctic is ice free and a loss of 0% there was no Summer. Ice-free-ness implies the sheet starts phasing out somewhere in the future. Actually this is already happening and it is accelerating. The real question is when will it hit the ground? Having 100% ice loss eliminates all room for discussion, because there is no such thing as 110% loss, 100% loss simply means game over.[MORE]
Surprisingly the percentage of loss was fairly stable until 2001 - the last year with a loss below 60%. In 2011 the loss was already above 80%. Assuming the first ice free September in the Arctic will happen after 2020 leads to strong cognitive dissonances occurring on author's side.