The graph shows the percentage of papers using data obtained by the team of authors ("without Archive data usage"), obtained from the ESO Archive ("Archive data only"), and obtained partly by the team of authors as well as from the ESO Archive ("Archive plus new data"), respectively.
Information about use of archival data for observations by VLT/VLTI and Chajnantor facilities is available since the start of operations of the respective telescopes and instruments. For La Silla facilities, this information is only available starting in publication year 2000.