> 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%

I know it doesn't really matter but this sort of wording does make me curious

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