There have been four referendums in the modern Poland:   A referendum on a proposed EU constitution was planned in 2005, but has been put on hold after the rejection of constitution by French voters. The referendum in Portugal is called by the President of Portugal (if he so decides), on a proposal submitted by the Assembly or the Government. Referendums are binding if turnout is higher than 50% of registered voters. Citizens of Portugal have the right to submit to the Assembly an initiative for a referendum. The referendum can be held only on "important issues concerning the national interest". The referendum cannot be held on amendments to the Constitution, and some issues such as budget and competences of the Assembly. There have been three referendums in modern Portugal: All three referendums had turnouts of less than 50%, which meant they were not binding. Nonetheless, the winning option on all three referendums was honoured by the governments of the time. The Constitution of Romania defines that a referendum has to be called to suspend the President from office, or amend the Constitution. Moreover, a referendum can be called on matters of national interest by the President of Romania after consultation with Parliament. There have been 6 referendums in post-communist Romania:  The Constitution of the Republic of Serbia was adopted on a referendum held in 28–29 October 2006. The constitutional referendum passed with 3,521,724 voting a 53.04% majority. 3,645,517 or 54.91% voted on the referendum, which made it legitimate. There was an independence referendum in Slovenia on 23 December 1990. The turnout was 93.3% of all voters, of which 94.8% cast a vote in support of independence. It was the first such referendum in one of the then Yugoslavian republics. The results were announced on 26 December, and on 25 June 1991, the Slovenian parliament passed an independence law proclaiming Slovenia a sovereign country. This was followed by the Ten-Day War, in which Slovenian forces drove the Yugoslav People's Army out of the country. In 2015, Slovenia held another referendum on a bill legalizing same-sex marriage, which was rejected by the majority of voters. In a referendum in Spain ("Referéndum para la reforma política", literally "Referendum for political reformation") on 15 December 1976, after the death of Francisco Franco, 94% of voters approved a Political Reform Bill to establish democracy. On 6 December 1978 a further referendum was held to approve a new Constitution.