> Just 1 in 3 (32.7%) [of] children and young people [...] a 36% decrease

So was it half of the kids before or two thirds?

    51.1% - 36% = 32.7%
    68.7% - 36%. = 32.7%

Since they do use "percentage points" further down, presumably it was 51% in 2005

I have to stop people from doing this in presentations all the time lol. Just say "Runtime decreased from 117s to 34". It is really easy to mentally compare two numbers; it is much harder to start with "Runtime decreased by 71% to 34s" and find the old value. Equally brief, never any ambiguity, easier on the mind, and no weird explosions as you approach zero.

I'd wager it's the first (51.1%). Mostly because I simply cannot imagine that nearly 70% of kids in 2005 enjoyed reading. That seems too high. Based on..? My vibes.