Sources
Datasets

Metropolitan Museum of Art: Annual reports
To realise this study, we used contents of the annual reports available from 2009 to 2017.

Louvre: Annual reports
Data used to created graphs have been selected in the annual reports available on the Louvre website.

Metropolitan Museum of Art: Data base
To obtain elements about accessions and credit line, we use the data base created by the Metropolitan Museum of Art. Available on Github, these data are artworks linked to the public domain.
Methodology
Metropolitan Museum of Art : Derived Dataset
We derived two new features from the Credit Line. The first is the Acquisition Date, the other is the Acquisition Type. To improve the missing values, we also used the Object Number which sometimes have the year in it.