Debris discs and comet populations around Sun-like stars: the Solar
  System in context
  Numerous nearby FGK dwarfs possess discs of debris generated by collisions
among comets. Here we fit the levels of dusty excess observed by Spitzer at
70$\umu$m and show that they form a rather smooth distribution. Taking into
account the transition of the dust removal process from collisional to
Poynting-Robertson drag, all the stars may be empirically fitted by a single
population with many low-excess members. Within this ensemble, the Kuiper Belt
is inferred to be such a low-dust example, among the last 10% of stars, with a
small cometary population. Analogue systems hosting gas giant planets and a
modest comet belt should occur for only a few per cent of Sun-like stars, and
so terrestrial planets with a comparable cometary impact rate to the Earth may
be uncommon. The nearest such analogue system presently known is HD154345 at
18pc, but accounting for survey completeness, a closer example should lie at
around 10pc.
