This may not be what you are looking for, but I was a contributor to an edited volume, Political Corruption in Comparative Perspective, which came out in 2012, published by Ashgate.   Its an amazing collection, but, so far, I haven't figured out how to add an edited volume in which I was only one of seven contributors to Researchgate

I am not aware of any specific database, but you may be able to do some creative searching on the Factiva news database. I have done so to create a dataset on corruption perceptions in Victoria, Australia. I would suggest searches along the lines of (prime minister or premier or president [etc]) and corruption and speech). Other terms like 'address' may be useful.

If you follow this route, be warned - there was a deal of manual editing before I was happy with the set I created. For more on the methodology, see Masters, Adam & Graycar, Adam (2015). Media reporting of corruption: Policy implications Crime Law and Social Change DOI: 10.1007/s10611-015-9595-1 published on-line (I am yet to load it into Researchgate)

Good luck with your research.

Hello Mergen,

I do not know if this dataset would help You, but is a worldwide comparison. 

GLOBALSTAT.EU

http://www.globalstat.eu/en/GlobalStat/Governance/Corruption%2b%2b%2bGovernance%2b(general)/Control%2bof%2bCorruption%2bIndex-333-

Best wishes, P.

For an article on corruptionframes in Baltic presidential speeches we (Karin Hilmer Pedersen and I) collected more than 1.000 speeches and stubs covering a decade in the three countries. The foreign ministries were quite helpful. Naturally we had to use computer assisted analysis with that number. See (in Danish- sorry )Johannsen & Pedersen (2012) "Korruption: strategisk politik og nationsopbygning : En sammenlignende analyse af baltiske præsidenters taler mellem 1998-2009" w