Moscow, Shawwal 21, 1436, Aug 6, 2015, SPA -- The devaluation of the Russian rouble since May reached 30 per cent versus the US dollar on Thursday, with the decline expected to continue through the summer, according to dpa. The rouble surpassed 64 per dollar in Moscow trading, compared with 49 on May 18, as oil prices tumbled. Oil is one of Russia's main exports, and the rouble's value is tightly linked to the commodity, which has experienced a boom in supply over the past year pushing prices down. --SPA 16:52 LOCAL TIME 13:52 GMT www.spa.gov.sa/w