 Complete the following phrase:  A three-question referendum was held in Bulgaria on 6 November 2016 alongside presidential elections. Voters were asked whether they supported limiting public funding of political parties to one lev per year per valid vote received at the previous elections, the introduction of compulsory voting in elections and referendums, and changing the electoral system for the National Assembly to the two-round system. In order to be binding, the number of voters participating in the referendum must be equal to or higher than the number who voted in the 