The Shiller P/E ratio – based on average real (inflation-adjusted) earnings from the last ten years – is at 27.08, with a mean and median of 16.59 and 15.96, respectively. And, in February, the forward 12-month earnings P/E ratio, which uses managers’ future earnings guidance, reached an 11-year high of 17.1, with the five- and ten-year averages standing at about 14 and the 15-year average at 16.