15% but not really
I assume the 15% quoted in the title is 15% of the members not 15% of all possible votes. IIRC this has been covered before but lest anyone forget. Only 25% of all possible votes are split evenly between members. The remaining 75% are split based on number of registered domains which means a small number of large registrars godaddy etc account for the vast majority of all castable votes. That's the real reason not many members bother to vote, their vote is worth near enough sod all!