It's going to get a lot bigger, mainly because of growing population. We're seven billion people today heading towards at least nine, probably nine and a half before we're done.
只会与日俱增，主要原因在于 人口成长，目前地球上有70亿人口 逐渐朝90亿大关迈进 我们离开人世前，或许将成长为95亿人口