For the 5th straight year, impersonator bots were the most active bad bots, making up 24.3 percent of all bot activity. Nitol malware was the single most common bad bot responsible for 0.12 percent of website traffic, Impervas Bot Traffic Report 2016 is based on analysis of over 16.7 billion visits to 100,000 randomly-selected domains on the Imperva content delivery network from August 9, 2016 to November 6, 2016.”]
Source: https://www.csoonline.com/article/3166589/study-1-in-3-website-visitors-is-an-attack-bot.html