years? >> it really depends. if you look at, for example, 1930s, buildings completeded. 1929, 1931, 1932. it tends to come, if you like, just a couple years after. >> this is no surprise here because booms in buildings will always be followed by a downturn. would you agree with that? i mean, it's just a natural thing. >> i think it's the fact that we have these building booms which are erratically timed and come at particular points in the cycle, business cycle. and it's not that we can necessarily just see if you like regular building cycles. they are particularly timed towards financial crisis. >> speaking of financial crises to come on the skyscraper index, you'd have to put china right up there, wouldn't you? >> we would. if we look at building booms, people can rest a little bit easy because there isn't a world's tallest building