A recent study done by Charles Lada concluded that about 85% of stars in the Milky way were red dwarfs and only 25% of these had companions. So the number of single "system" stars is likely more than 66%. Previously accepted thought was that the number of systems was more than 50% and possibly 2/3 of all stars.
And, the accepted wisdom was that planets were unlikely to form around stars in systems.
