Choose the most recent year's reports from the Ohio Attorney General's office Reports page. The office publishes statewide data including incidents reported by county and agency.
Ohio"s Office of Criminal Justice Services compiles the data reported by local law enforcement agencies to the FBI's Uniform Crime Reporting Program on their Crime Statistics and Crime Reports Page:
http://www.ocjs.ohio.gov/crime_stats_reports.stm
Annual statistics by county and reporting agency are provided as Excel files. Click on the "Crimes by County" Statistics file for the most recent available year.
The Ohio State Highway Patrol reports "year to date" statistics for enforcement of Ohio's law prohibiting operation of a vehicle while under the influence of alcohol or drugs.
Visit their Statistics website and use the pull-down box on the right under the state map to get statistics by county or OSHP district.
http://statepatrol.ohio.gov/statistics/
For detailed county activity reports, including OVI arrests, consult the 2017 Operational Report beginning on page 38 of the PDF file.