PRISTINA - kosovo marked the fourth anniversary of its declaration of independence Friday under a cloud as it struggles to assert authority over defiant ethnic Serbs and tackle rampant corruption. Just two days before the anniversary 99.74 percent of Serbs in northern kosovo , which borders Serbia proper, rejected the ethnic Albanian government in a referendum meant to highlight their anger at concessions Belgrade made in talks with Pristina. Although the vote had no significant impact on the political scene.