Cyber-insurance purchases have doubled in five years in the US following high-profile disruptions from the WannaCry and NotPetya attacks, a Marsh report shows.

Last year 38% of the global broker’s clients bought cyber cover, up from 19% in 2014, with growing reliance on technology also raising concerns over potential disruption.

Health and education are the largest purchasers, but buying rates in hospitality and gaming have increased more than any other sector over the past three years.

Recent attacks show cyber threats have evolved to create business interruption and supply chain disruptions, as well as data breaches and theft, and more companies consider themselves at risk.

Insurers are refining their approach and are more carefully defining the boundaries of property, casualty and cyber policies.

“Property insurers, for example, are generally no longer willing to provide coverage for business interruption caused by network intrusions,” Marsh says. “Those losses are increasingly expected to be covered under cyber policies, which have expanded to respond to a wide variety of potential risks while still being competitively priced.”

Last year average cyber policy limits bought by companies with more than $US1 billion ($1.4 billion) in annual revenue increased more than 25% to $US62.4 million ($86.5 million).

Average cyber limits for all companies increased 11% to $US20.9 billion ($29 billion).