Created by Philip Keefer and his colleagues at World Bank.
Downloadable here (updated, Jan 2016)
Annual data is available since 1975.
Notice that this dataset's coding refers to January 1st of every year, rather than 31 December of every year as is the case for other political datasets such as POLITY IV. Therefore, when you merge DPI with, say, POLITY IV, year t in DPI should be matched with year t-1 in POLITY IV except for cases in which POLITY IV variables change on January 1st (such as Comoros in 1985, Iran in 1982, and Nigeria in 1984).
Used for the percentage of legislative seats held by opposition parties in Beaulieu and Hyde (2009).