Final answer:
According to the report mentioned, it is stated that a specific percentage of society believes that mass killings signify broader social problems.
Step-by-step explanation:
Subject: Social Studies
According to the report mentioned, it is stated that a specific percentage of society believes that mass killings signify broader social problems. However, the exact percentage is not provided in the question. Therefore, we cannot fill in the blank without this information. However, it's important to note that public opinion on any issue, including social problems, can vary widely within society.