Spain's population has grown significantly over the past century from 18 million in 1900 to 46 million currently due to natural growth and immigration. The population is characterized by having slightly more women than men, with those aged 16-64 representing 66% of the population and those under 16 and over 65 each making up around 17%. The main economic sectors in Spain are services, industry, and agriculture, with 65% of the active population working in services, 30% in industry, and 5% in agriculture.