Data from companies or websites can sometimes be biased and misleading. Reliable statistics are generally produced by government agencies, dedicated statistical departments and other official organisations:
Office for National Statistics
UK's largest independent producer of official statistics, including business, employment, population, health and environmental data.
Government Departments & Agencies
UK government information, data and reports on matters such as immigration, tobacco, social housing, sport, gambling, the environment, etc.
Eurostat
Statistics from the European Union. Includes data on health, education, food and packaging, tourism, population, climate change and more.
Data.gov
USA Government's open data. Information on retail, trade, climate, health, education and other sectors, at a federal, state, and local level.