London skyscraper rents aren't the most expensive in the world, but they are rising the fastest.
Asia dominated the list, with nine cities in the top 21, while North America had six and Europe had four.
But it was London that had the biggest growth in rents over the six month period, at 9.68%, with Singapore and San Francisco a distant joint second at 4.76%.
Skyscrapers are defined in the report as commercial buildings over 30 storeys.
Singapore was the only city where skyscraper rents significantly decreased for the period, with the 4.75% drop attributed to over-supply and diminishing occupier confidence as a result of the slowdown in the Chinese economy.
Ally McDade, an associate at Knight Frank's Research team, said growing skyscraper rents were down to lack of space and a burgeoning tech sector.
For the second time in twelve months, London is the fastest growing office tower market in the world due to its diversity of occupier demand and constrained supply.
In the U.S., the rapid expansion of the tech sector is underpinning rental growth for towers in cities like San Francisco and Boston. Interestingly, Mumbai's emergence as a top performer has benefited from growth in tech, as it surpassed financial and business services as the top occupier of office space in the second half of 2015.
Check out the cities with the most expensive skyscraper rents below: