Ratio (%) is calculated as "Buy support / Market cap". You can also see separate metrics for both "Buy support" and "Market cap" in the same row.

We count all buy orders (on all prices). It's true that low-hanging orders might be cancelled before they are executed. We've decided to count them anyway, because even low orders provide support during flash crashes.

Flash crash horror movie: https://youtu.be/R7WfSTePuA0?t=171

This was possible because there wasn't much buy support. And that's ETH - imagine what can happen with lowcap altcoins.

P.S. The fact that some altcoins don't even have market makers is a little... unsettling, don't you think?