What fraction of Sun-like stars have planets?

The radial velocities of ∼1800 nearby Sun-like stars are currently being monitored by eight high-sensitivity Doppler exoplanet surveys. Approximately 90 of these stars have been found to host exoplanets massive enough to be detectable. Thus, at least ∼5% of target stars possess planets. If we limit our analysis to target stars that have been monitored the longest (∼15 years), ∼11% possess planets. If we limit our analysis to stars monitored the longest and whose low surface activity allows the most precise velocity measurements, ∼25% possess planets. By identifying trends of the exoplanet mass and period distributions in a subsample of exoplanets less biased by selection effects and linearly extrapolating these trends into regions of parameter space that have not yet been completely sampled, we find that at least ∼9% of Sun-like stars have planets in the mass and orbital period ranges M sin i > 0.3M_Jup and P < 13 years and at least ∼22% have planets in the larger range M sin i > 0.1M_Jup and P < 60 years. Even this larger area of the log(mass)-log(period) plane is less than 20% of the area occupied by our planetary system, suggesting that this estimate is still a lower limit to the true fraction of Sun-like stars with planets, which may be as large as ∼100%.