separations ([@fischer05]; [@sousa11]), a bias that seems to hold for stars beyond the main sequence (e.g. [@reffert15]; [@soto15]; [@jones16]). In comparison, recent work appears to show that stars that host lower-mass planets have a metallicity distribution that is indistinguishable from those that host no known planets at all ([@udry07]; [@jenkins13a]; [@sousa11]; [@buchhave15]). Furthermore, @jenkins13a suggests there exists a boundary that delimits a planet desert for the lowest mass planets in the metal-rich regime. Such results show there is a fundamental relationship between the proto-planetary disc metallicity and the mass of planets that form in these discs, indicating further study of the planetary mass function and its relationship with metallicity is warranted.

Since metallicity plays a key role in the formation of the observed planetary systems, explained well by nature’s merging of core accretion and planet migration (e.g. [@ida04]; [@mordasini12]), and now we are reaching a population size where less obvious correlations can reveal themselves, studying the current population of known planets can provide a window into the fundamentals of planet formation and evolution for the stars nearest to the Sun.

In 2007 we started a radial velocity planet search program on the HARPS instrument at La Silla Chile, with the 