All this work was done secretly. The public face of Blue Book continued to be the official Air Force investigation of UFOs, but the reality was it had essentially been reduced to doing very little serious investigation, and had become almost solely a public relations outfit with a debunking mandate. To cite one example, by the end of 1956, the number of cases listed as unsolved had dipped to barely 0.4 percent, from the 20 to 30% only a few years earlier.