I'm suspicious that this is missing a lot of data, and if it's only a portion of the market and biased in which data is included, that would make it less useful.

Google is one of the leaders in terms of corporations buying offsets, and my understanding is that they have a high bar in terms of quality/effectiveness. They offset all carbon emissions and have back-dated that to the beginning of the company. And yet they're nowhere to be seen on this.

Am I missing something about what this data is supposed to show?