A recent study that was done by Wesley Traub. But he estimates that there are about 34% with the error margin of +-14% of sun like stars with Earth like planets in there habitable zone. But this study has the potential for higher error rates, as it is only based on data from 136 days. But he also had to base his study on data from short period planets that are already known. But from what other media is reporting, it seems however that this study is all good.
But the hypothesis in this study means that there might be a lot of life out in the universe. But this does not equal that all of it is like humans and have developed a civilization. But all considered, I would say that chances of that are not too bad either.