Have you ever had a hankering to tweet at UK Prime Minister David Cameron? He tweets as @Number10gov. What about South Africa’s President Jacob Zuma? You can find him at @SAPresident. And Russia’s President Vladimir Putin? That’s @KremlinRussia_E, for the English-language account — but don’t expect a reply there, it’s more or less just a news feed. Sensing a trend? Many world leaders have begun using Twitter — 75% of them, according to Digital Daya, which advises politicians on new media use. “Analyses as of December 2012 reveals that 75 percent, or three out of four heads of state, are at present on the social media site Twitter,” wrote Digital Daya in a recently released report. That number has more than doubled in the last two years.