I that article, 267% represents the highest increase seen. It's not any sort of average. It's odd that it's reappeared in this article now.
And, here's a bit of reading on the process for a customer requiring >75MW: https://www.dlapiper.com/en-us/insights/publications/2026/03...
It's frustrating seeing this issue framed as a big tech issue, and not as an issue of government refusing to govern. Not only are local governments welcoming these data centers, but they're giving them tax breaks to move into town. If it's going to cause the quality of life of your citizens to supply these data centers with water/power, the least you could do is not give them a tax break for doing so.