I am looking for the best objective source to compare corruption in Russia to other countries. The often cited Corruption Perceptions Index (as far as I can tell) is not objective since it is based on subjective opinion of mostly western experts. The Global Corruption Barometer would be great, except that Russia is not included in the 2013 version cited on wikipedia. Russia publishes some data in the Антикоррупционная инициатива бизнеса, i.e. business anticorruption initiative, but this does not allow comparison to other countries.
It is 2016 numbers, but here is The Global Corruption Barometer for Russia.
You can click around the map to compare with other countries.