Net unrealized capital losses increased to more than $13 billion at U.S. life insurers in 2008, up from $8 billion in 2007.

Highline Data, a unit of Summit Business Media L.L.C., Erlanger, Ky., is reporting that finding in an analysis of data drawn from the company’s financial databases.

In 2008, 9 of the insurers included suffered net unrealized capital losses that were greater than $500 million, Highline Data says.

Separate account assets fell 5.5%, while general account assets fell just 2.3%.

Net premiums fell 9.7%, and net gain from operations dropped about 27%.