Natural catastrophes caused global insured losses of about $31 billion in 2013, according to an analysis Munich Reinsurance Co. released on Tuesday, Business Insurance reported. (Registration required.)  That level of losses was far less than the 2003-2012 10-year average, which was approximately $56 billion, according to the company. However, the 880 natural catastrophes recorded last year exceeded the 10-year average of 790. Insured natural catastrophe damage in the United States totaled approximately $12.8 billion, less than half of the 10-year $29.4 billion average. Insured losses from U.S. thunderstorms reached about $10 billion, despite the lowest observed tornado count in a decade, according to the analysis.