"Volcanoes of the World" is a database describing the physical characteristics of volcanoes and their eruptions. This search returns volcanic emission activity data sorted by date. As of February 2017, all emissions data has been provided by Simon Carn using NASA SO2 data, captured using satellite-based instruments. NASA launched the Total Ozone Mapping Spectrometer (TOMS) in 1978, which provided the first space-borne observations of volcanic gas emissions. Numerous satellites capable of measuring volcanic gases are now in orbit.
Results may be downloaded into an Excel spreadsheet. The emissions available here can also be seen graphically using the Eruptions, Earthquakes & Emissions web application.