The average premium for a health insurance policy purchased in the individual market in 2005 was $3,664 for individuals and $5,568 for families, according to a new study from the Agency for Healthcare Research and Quality.

In general, the study finds that older purchasers pay higher premiums than younger purchasers, reflecting the relatively higher health care costs that people incur as they get older. In 2005, average premiums for single coverage were $1,580 for purchasers aged less than 40, $3,325 for purchasers aged 40 to 54, and $4,288 for purchasers aged 55 to 64. Nationwide, the total number of policyholders with individual health insurance was 6 million in both 2002 and 2005, the report says.