I have seen 28% at Stanford (four years ago), 23% for Brown this past year ACT, 28% for Princeton 4 years ago. These are all numbers that were either in their recruiters manuals or published online. I’m assuming that 25% is a good number in today’s environment of rising tests scores and schools becoming more inured to them.
Your EC’s are fairly ordinary in that even where you delved deep you have no state or national recognition. If not for legacy status, I would put your chances in the 75% that eventually get denied. I have no idea what the pull from being a legacy will be. This is all just my opinion - others may feel differently. Good luck with everything!