Looking back at it, it went from -5 to +8 (but with no 6 or 7...). I could count all the votes for scores below 1 out of 10 as 1 out of 10, but I'm sure you'd get a completely different result to what it would have been if it was a normal 1 to 10 poll.
For the record, if I just take the poll as it is the score is 0.5 out of 10. If I count all the votes below 1 as 1 out of 10, the score would be 1.9 out of 10. I suspect the real score would have been something like 3 out of 10 if it had been a normal poll.