So for an indie developer publishing a game without releasing a demo version, they've instantly cut their potential market down to 62%.  When you consider that 63% of players either always or usually play the demo before buying an indie title, and only 12% state that they never play the demo first, it confirms that an effective demo is one of the most important marketing tools for indie developers.  So if you're a new indie developer, don't underestimate the power of a demo version that draws players in enough for them to want to pay to continue the experience.