The maps below link to files which display the number of Landsat scenes that are archived at the USGS EROS Center, per satellite/sensor, per year. The last map links to a file that contains all satellite/sensors and years.
Note: These maps only show what data is held at the USGS EROS Center at the time of file creation. There may be some data not yet added to the USGS archive, as they were downlinked to various International Ground Stations over the years. (The Landsat Global Archive Consolidation (LGAC) effort started in 2010, with a goal to consolidate the Landsat archives of all ground stations worldwide into the USGS EROS Center archive.)
These maps are updated biannually in July and December to reflect the Landsat archive holdings at the USGS EROS Center.