"StackOverflow probably has a 90% cache hit ratio (86% of visitors are from google that land on some question asked some days or months ago)." For a fair analy

"StackOverflow probably has a 90% cache hit ratio (86% of visitors are from google that land on some question asked some days or months ago)." For a fair analysis, you need to consider that people keep adding answers and comments to questions, specially if it is covering an interesting question or technology. (And what happens to the cache then?)