The agency also prepares a national port risk assessment every two years. The agency assessed the relative risk to 168 ports of entry in 2006 and 220 in 2004. Regional intelligence analysts, in consultation with other sources and port operational staff, complete a questionnaire detailing port demographics, traffic volume, enforcement, and intelligence information. The 2006 risk assessment ranked 23 ports as high-risk and included information on suspected criminal and national security risks, as well as the risk of irregular or illegal migration of people.