From the United Nations Development Programme, a composite index evaluating health, education, and living standards across the world's countries. 1980 - 2018.
Statistical data, including time series data, for over 200 countries. Variables include government expenditure, trade, infrastructure and media, domestic conflict event data, elections, legislative process, numerous political measures and international status indicators. Covers 1815 - current.
All countries, 1900-present, on various measures of democracy. Measures these democratic qualities: Electoral, Liberal, Participatory, Majoritarian, Consensual, Deliberative, and Egalitarian. Also provides subcomponent measures re. elections, judiciary, etc.
Measures regime characteristics (democracy/autocracy) for all states over 500,000 from 1800 to 2018. Also find other data on conflict and peace at this link.