Global Market Data

Swiss Re Sigma Explorer - The gold standard for global insurance data. Provides downloadable data on natural catastrophes, world insurance premiums, and economic outlooks.
AM Best Rating Services - Global credit ratings and financial data for insurance companies. Good for finding top 20 rankings by region.
Global Federation of Insurance Associations (GFIA) - Represents insurance associations worldwide; useful for finding high-level regulatory trends and member associations in specific countries.

North America

National Association of Insurance Commissioners (NAIC) - The primary source for US regulatory data. Their "Market Share Reports" section is essential for US market rankings.
Insurance Information Institute (III) - Excellent for consumer-facing data, white papers, and "Facts + Statistics" regarding the US property/casualty market.

Insurance Europe - The main federation for European insurers. Provides the "European Insurance in Figures" dataset which is crucial for EU market rankings.
GDV (German Insurance Association) - The primary source for the German market (Europe's largest), offering detailed statistical yearbooks.

International Association of Insurance Supervisors (IAIS) - While global, they are headquartered in Basel and heavily influence Asian regulatory frameworks. Their "Global Insurance Market Report" (GIMAR) is key.
Monetary Authority of Singapore (MAS) Insurance Stats - Highly detailed data on the Singaporean insurance market, often used as a benchmark for SE Asia.