Google released its annual report on combating bad ads during the past year, which includes the number of such ads turned off and the number of bad sites removed within 2017.
In addition, Google shares details of its policies that help prevent financial incentives behind malicious ads and websites, including those promoting misleading, inappropriate or harmful content.
In 2017 alone, Google removed over 3,2 billion ads that did not comply with the company's advertising policies, which translates to more than 100 malicious ads per second. This practically means that the majority of malicious advertising experiences, such as malvertising and Phishing scams, before infecting users.
It's made of feature that, over the past 15 years, Google has invested in technology, policy-making and people skills to help fight ad fraud and malware and content.
2017 was, however, the year that the company succeeded in removing most of the malicious actors from on-line οικsystem than any other time, but also at the fastest pace.
More details can be found in the relevant section blogpost: https://www.blog.goοgle/