  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.

Earth and Planetary Astrophysics;Astrophysics of Galaxies