Why not add this to chess puzzles

I noticed that when i finish a puzzle they give the rating of the puzzle and the number of times the puzzles has been attempted so why not give the percentage of how many solved the puzzle. This is something that user would so obviously want to know and would be so easy to add that I must be missing it but I've looked all over and don't see it.

This percentage is probably close to 50% for all puzzles that have been played frequently enough. That is how the rating system works, it adjusts the rating to a point where the puzzle is solved half of the times.

This could be distorted by players choosing to do easy or hard puzzles, but that would affect all puzzles the same.