What is "Paid Share"? - Keyword Destination

"Paid Share" is the breakdown of search referral share generated by paid clickthroughs from this particular keyword

For example: If a site receives 10% of its traffic from keyword: "cars", the Paid share of that traffic might be represented as 20%/80%, meaning 20% of the 10% was through paid search referrals and the other 80% was generated through natural search.

Paid and Natural data for Broad Match reports is often a long tail of matching terms referring traffic to a given site. In some instances, Paid Share is estimated based only on the highest-volume matching terms.