office more unusual. During his time leading Russia, Putin has dealt with four separate U.S. presidents as well as four British prime ministers and two German chancellors.

The Kremlin may also dispute the methodology, as Putin wasn't president for all of his time in office. He first became prime minister of Russia on Aug. 16, 1999, before entering the presidential office May 7 the next year. Later, as the Russian Constitution limits the president to two consecutive terms, Putin stepped out of the Kremlin in 2008 while his prime minister, Dmitry Medvedev, became president.

However, most analysts agree that Putin still held the real power during that "tandem" presidency. He returned to the presidency in 2012.

Putin's increasingly lengthy time in office may not appear to be a problem to manyRussians - as widely noted, his approval ratings remain extraordinarily high. He is widely expected to stand to be nominated as a presidential candidate again for next year's elections, according to reports in the Russian media.

But there are some signs of a malaise setting in; some Russians have begun to share cynical jokes about Putin that resemble those told during the Brezhnev era. Turnout in recent local elections was low, and some polls suggest that a significant minority of the country is not sure whether they want Putin to run for reelection.

Still, Putin is likely to win next year's election if he runs - potentially putting him in office until 2024 (after Medvedev left office, presidential terms were increased from four to six years). He could choose to