CREATE TABLE table_name_19 (gdp__percentage_of_eu__2012_ VARCHAR(255), gdp_in_s_billion_of_usd__2012_ VARCHAR(255))
What is the GDP % of EU in 2012 of the country with a GDP in billions of USD in 2012 of 256.3?
    
SQL: SELECT gdp__percentage_of_eu__2012_ FROM table_name_19 WHERE gdp_in_s_billion_of_usd__2012_ = 256.3