GGC cache hit rate refers to the number of times that the cache is able to successfully serve content instead of having to retrieve the data from a different location. In other words, if the content is available on the GGC and served from it, that's a "hit." Hit rate varies by network based on:
The number of users served by the cache
The size and type of GGC node
The number of nodes deployed in your network.
We typically see hit rates of 70% to 90%.