A couple of years ago, I inquired about my lifetime activity.
It took a week or so, but I was given a lengthy PDF that detailed all of my stay/night/points history. I had saved every reservation confirmation email and check-out folio email. It took a couple of days to cross-check, but Hilton's data matched up exactly with mine.
Since then, I've been keeping an Excel sheet that tracks everything, including some stats (bonus points earned per dollar spend, nights per brand, number of unique properties per year, nights and spend per property, etc.)