Quatro "Overall Score" calclulations?

I just can't make the scores add up for Quatro. Take top place The-Hawk's current scores on the quatro list for an example:

114 93 96.7 145.3 51.4 57.6

These average out to be 93, yet his published overall score is 89.5?

What's the formula used for the Overall Score?

Thanks

The Gauntlet subevent is weighed heavier than the rest.