Each one of the 102 points plotted below represents a different country.
Correlation does not prove causation, but there are many other reasons to believe this is true: corruption impedes economic growth.

GDP per capita based on 2000 data available at http://www.cia.gov/cia/publications/factbook/

Corruption Score is based on the TI Corruption Perceptions Index 2002, available at http://www.transparency.org/

For display purposes, the corruption score here is 10 minus the TI score, so that a higher score indicates higher corruption.
Source data is available here.