What is the relationship between number and steam in the context of the input sentence. Choose an answer from: product/material produced; manufacturer; distributed by; industry; position held; original broadcaster; owned by; founded by; distribution format; headquarters location; stock exchange; currency; parent organization; chief executive officer; director/manager; owner of; operator; member of; employer; chairperson; platform; subsidiary; legal form; publisher; developer; brand; business division; location of formation; creator.

What’s also interesting is that we have a number of steam turbines in the fleet – in the global fleet, they’re due to come off charter over the next two, three, four, five years.

Answer: distributed_by