BUCHAREST (Reuters) – Romania is considering changing its tax system, Prime Minister Nicolae Ciuca said on Wednesday in a surprise announcement, and his leftist coalition partners said they wanted to replace the current flat income tax rate with a progressive one. Ciuca’s centrist Liberals introduced a flat tax of 16% on income and profit in 2005, boosting budget revenue in the European Union country, which is plagued by vague legislation, bureaucracy and corruption. The Social Democrats, the largest part in the ruling coalition, have advocated for progressive taxation for years. Ciuca said th…