I don't know if this helps, but we have a SQL Server with 72 GB of memory. It typically runs between 85% and 88%, but occasionally spikes to 92%. I have read that SQL Server will consume as much memory as you throw at it and want just a little bit more. No matter how much more you give it, it'll always use more. 😀

I know it uses as much as it can to improve performance through caching and query plans and I've never found an upper limit.