AM Best has come out with its annual ranking of the world’s largest insurers.The rating agency looked at the largest companies — ranking them both by assets and by premiums written and found different factors affecting both lists. None of the companies listed are domiciled in Bermuda. Topping the list of top 25 largest insurers by assets only was Japan Post Insurance Company, followed by AXA and Allianz.But when it comes to the rankings by net premiums written, the Best said it noticed an interesting trend — that Asia is showing strong growth. For the first time ever, four Japanese companies have made the top ten list of largest insurers (as measured by net premiums written). That also represents the greatest presence of any single country.Japan Post moved up from fifth to third place; National Mutual Insurance Federation held steady in sixth place; Nippon Life jumped from 12th-largest to seventh and Meiji Yasuda Life jumped from 20th to eighth.The rating agency said it’s no accident that the Japanese companies are moving up rapidly on that list because for the past few years the top Japanese insurers have indicated they would be aggressively pursuing growth overseas in developing markets outside of Japan.That’s contrary to what’s going on in Europe, AM Best says, where there is stagnation due in part to the Eurozone crisis and rising solvency standards. Some of the top insurers in Europe such as Aviva and Generali of Italy dropped quite a bit as far as their premiums go in the past year. Much of that, analysts say, is on the life side where they’ve been hurt both on the investment side as well as far as premiums go.AM Best also found that in the US, there is continuing fallout from 2008 and AIG’s financial crisis. The government stepped in to bail out the company and to repay that debt, AIG started selling assets causing them to fall in the rankings. AIG dropped 13.7 percent in net premiums written, falling from the 13th-largest to the 19th-largest by net premiums written, and dropping 18.7 percent in assets to fall from the fifth to the eighth-largest.Companies that bought AIG assets like MetLife, Prudential Financial and UnitedHealth Group however, have risen, Best said. MetLife grew faster than any other company in net premiums written in part because it bought an AIG asset. Prudential Financial grew faster than any other company in assets, also partly because it bought an AIG asset.