The revolution set the template for uprisings in Egypt, Libya, Syria and Yemen which have re-shaped the political landscape of the Middle East. "We have seen a new movement in Arab nations," TI Managing Director Cobus de Swardt told Reuters.
"You now have not only a push for basic human rights but also for public accountability. The lack of public accountability has been recognized as a major problem."
Egypt fell to 112th from 98th, with a CPI of 2.9, and Syria slipped to 129th from 127th. Yemen and Libya shared 146th place last year and dropped to 164th and 168th this year respectively.
De Swardt said change now appeared much more driven by the demands of grassroots movements - which this year also included heavy anti-corruption protests in India - than by governments being proactive in improving transparency.
"The last 20 years have seen pockets of that (grassroots action), but it is arguably now in the Arab Spring and the Indian Summer where it is the most widespread and very much driven by good governance demands," he said.
Heading the index -- in which a score of 10 indicates a country with the highest standards, and 0 as highly corrupt -- was New Zealand with 9.5, followed by Denmark and Finland, sharing second place with 9.4. New Zealand has topped the table every year since 2006.
Somalia and North Korea both scored 1.0, with North Korea being included for the first time in the index's 16-year history. De Swardt said there had previously not been enough data to include the Asian country.
"There are no checks and balances in North Korea, no public accountability and total political control of the judiciary. And on top of that, civil society as we know it does not exist there," he said.
Most worrying, he said, was that high levels of corruption fundamentally undermine food distribution, painting a grim picture for North Korea, where the United Nations Children's Fund (UNICEF) has warned of a coming "nutrition crisis".
About two thirds of countries ranked in the index this year scored 5.0 or less.
However, TI identified Russia, Iran, France, the United Arab Emirates, Poland and Cuba as states where improvement had been made over the past year.
By contrast, it highlighted Haiti, Zimbabwe, India, Saudi Arabia, Czech Republic, Ireland, Qatar and Costa Rica as nations where perceptions had deteriorated