Also, U.S. citizens will happily list the entire high school summer reading list that they "loved" over ten years ago, which of course they didn't actually read then either.
Just my cynical take on it. Still interesting data.
Edit: I forgot the word "everything" in "actually read everything".
I am willing to put it out there that people are embarrassed to admit certain books, so I'll be the first to admit that I think most people prefer "Blood Meridian" to "The Road" but don't want to put their full authenticated legal name to the claim. I don't claim blood meridian is some kind of great literature, but as an action book with memorable characters and local flavor...
Another book with gallons of local flavor and just "weirdness" and interesting is Lucifers Hammer and that's another "I'm not going to admit in public, but ..."
How about "Post Office" another, uh, questionable tome.
There is also an age aspect. Some young kid claims to have slogged thru all of Gibbon, he's probably a history student or more likely lying, but I'm an older guy and I really did invest the time reading the whole decline and fall. I think it was worth it, at least the first half or so.
But I know a lot of people of liked it, so I can see why it is on the list, even if I didn't like it.