Go to Transparency International and take a look at Global Corruption Report.

Also, launch key word searches in the following databases:
ABI/Inform
Digital Dissertations
EBSCO BSC
EIU Country Reports

Use the Library Catalog -- launch a key word or phrase search, i.e. 'global AND corruption' and click SEARCH to locate texts similar to the following:

• Corruption and The Global Economy by Kimberly Ann Elliot (call number: 364.13 C817)