Left: mean detection probability map of the A-F sample as function of the mass and semi-major axis of the substellar companion. A uniform grid distribution has been used to generate the population, but the formation limits derived from the gravitational instability models excludes for each star the planets that do not fulfill both criteria. The detection maps from LOCI and nADI algorithms were used with COND03 (Baraffe et al. 2003) evolutionary models to convert from contrast to mass. Contour lines are regular from 0.5 to 0.9 plus one at 0.1. Right: corresponding estimate of the upper limit, with a confidence level of 95%, on the fraction of stars from the A-F sample that harbor at least one object companion in the same semi-major axis range. The curves for 25 M_J, 18 M_J, 13 M_J, and 10 M_J have been plotted since lower mass planets are not allowed to form via the disk instability mechanism.