From this article:

“In the recent survey, respondents rated critical security threats. The results include viruses and worms, a 7.6 rating (“1” indicated “no concern at all,” while a “10” meant “extremely concerned”); outside hacking or cracking, 7.1; identity theft and phishing, 7.0; spyware, 6.8; denial of services, 6.6; spam, 6.3; wireless and mobile device viruses, 6.2; insider threats, 6.2; zero day threats, 5.9; social engineering, 5.9; and cyber-terrorism, 5.6.”