Dublin office rents increased by 32 per cent over the past year, the largest increase of 50 cities surveyed by the US research group, CB Richard Ellis. The city is ranked 18th in the world for the group's Global 50 Index, charging $50.63 sq. ft (€49.46), cheaper than Birmingham, Glasgow, Manchester and Edinburgh but more expensive than Warsaw, Zurich and Munich. Central Tokyo, at $131.36 sq. ft (€128.28), was the most expensive rent in the world, rising by 22 per cent over the year, the second highest increase worldwide. Vienna, in Austria, is the cheapest of the 50 cities, charging $31.17 sq. ft (€30.45).