Georgia high school students made slight improvements this year on end-of-course tests in U.S. history, economics, biology, physical science and English, according to new data released Tuesday by the state Department of Education.In April 2011, the state Board of Education approved a plan to phase out the Georgia High School Graduation tests beginning with the class of 2015. Officials say end-of-course tests, which began in Georgia last year, are a better measure of how much students have learned.“These reports include only the spring EOCTs,” said Merrianne Dyer, superintendent of Gainesville City Schools. “High school students will conclude the follow-up testing in July and at that time we will have a better overall picture of our summative performance.”Students showed the biggest gains in economics, with 77 percent passing, up from 72 percent last year.