NyQuil
Big F$&*in Q
Clearly the overall column is there for a reason, because it matters in calculating the overall attendance figures for each team. Besides the season isn't over yet so the numbers you provided aren't yet completed. Buffalo finished 21st in home attendance % last season for example and Vancouver finished 18th.
Why does road attendance matter?
If you're in a division with good home support, that number will be high no matter how bad or unpopular your team is.