I thinbk it's the ratio rather than any specific figures. My understanding is that bust and hips need to be roughly equal and that the waist needs to be 1/3 less than that more or less- which bears out what prudie just said actually.
I would strongly argue against the assumption that a 'perfect' figure (if such a thing exists) has to conform to the 'hourglass' shape.
However when I was a kid, and the "Miss World" competition was watched on TV by most of the population, '36-24-36' often seemed to be cited as 'perfection'.
What is the 'perfect figure'? It seems women have this idea of a perfect shape they should be, especially to appeal to men. Speaking as a man (and having heard what other men say over the years) men do not generally like the 'hourglass figure'. There are too many hard bits and bones sticking out! Wome think men like that - but most men prefer women to be a little more cuddly.
tinks my 'really' was aimed at Chris quoting the figures I'd already posted. It looks like I might have been questioning your figure which I wasn't and wouldn't x