Filled up at £1.11.9 this morning..... I'll happily take that!
Another factor can be governments selling it off cheap. As a nation we probably keep 25million litres or so as a national reserve for our military vehicles BUT it does degrade in storage so they will replace it routinely. If they have dropped 5 million litres onto the market that will have an effect as well.
Satellites surveying Siberia and Eastern USSR in the 80s found what they thought was underground water storage... turns out it was diesel... BILLIONS of litres of the stuff!!