FACTBOX-Mayoral election in numbers

LONDON (Reuters) - Voters in London go to the polls on May 1 to elect the capital's mayor.

Here are some key figures in the election:

5.5 million - total number of registered voters

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1.9 million - people who voted the last time in 2004

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12,000 - staff working in polling stations on May 1

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4,000 - polling stations