How near does it need to be to be near an all time high? If we say within 5% then it looks like, outside of the catastrophic period between 2000 and 2012, the graph spent the vast majority of its time there.

What does drawndown have to do with ATH? The SPX is ~50 points (1.3%) from its ATH right now (3663 as of Friday close) vs ATH of 3715 on 12/9. It's reasonable to say "close to ATH".

Edit: Corrected points and added percentage.

Depends on your tolerance band. If it’s zero, then only on days when you hit a new ATH can you count as “at ATH”.

If you set a 10% threshold, then you’ll have many more days “at ATH”.

My point is that actual ATH (versus “near ATH”) are comparably rare.