An annual measure of customer satisfaction finds public perception of their health insurers plummeting.

The American Customer Satisfaction Index (ACSI), which ranks companies on a 100-point scale, saw customer satisfaction with health insurance falls 2.7% to an ACSI score of 73 for 2010.

Among individual firms, the most precipitous drop in customer satisfaction was recorded by UnitedHealth, whose score fell seven points from a year earlier to an industry low of 65. By comparison, Blue Cross and Blue Shield dropped three points to 70 and Aetna fell two points to 68. WellPoint was the only health insurer to chart an improvement, gaining two points from the previous year to finish at 69.

“The cause of the customer satisfaction decline is not difficult to find—sharp increases in premium costs and deductibles are to blame,” Claes Fornell, a professor at the Stephen Ross School of Business at the University of Michigan and founder of the ACSI, said in a statement.

Life and property/casualty insurance fared better in the survey and tied with credit unions for the highest ACSI score in financial services. The aggregate score for the life insurance industry rose one point to 80, while property/casualty insurance was unchanged at 80. Northwestern Mutual maintained its top satisfaction ranking among life insurers but fell one point to 80.  New York Life and MetLife both achieved a score of 78 while Prudential tallied a 77.

For P&C companies, State Farm maintained the top spot, unchanged at 82, followed by GEICO, also unchanged at 81. Progressive and Allstate each fell one point to 79 and 78, respectively.

“Life and property & casualty typically do better with customers compared to health insurers because premiums are lower and policyholders have fewer reasons to interact with the insurance company, so there are fewer opportunities for things to go wrong,” Fornell said. “This is particularly true for life insurance—premiums typically are fixed for the duration of the policy, and once a policy is in place, a customer might never again interact with the insurer.