The third edition of the Role of Mining in National Economies report introduces an updated Mining Contribution Index (MCI) that synthesizes the significance of mining to over 180 national economies into a single number. The updated MCI incorporates a new indicator - mineral rents as a percentage of GDP. The MCI shows that many mineral-dependent countries continued becoming more reliant on mining despite falling commodity prices between 2011-2014. While the MCI provides a starting point for understanding mining's economic contributions, more data is needed to fully capture factors like employment and governance impacts. As data improves, future MCIs aim to provide a more nuanced view of how countries leverage mining for development.