Devon and Cornwall police have released the results of their latest campaign.
Police officers administered a total of 788 breath tests of which 163 were positive, refused or failed to provide, equating to 20%.
Last year the comparable figures were 776 breath tests with 132 positive, refused or failed to provide which equates to 17%.
Police say anyone convicted of drink driving can expect to be banned for at least 12 months, and receive a fine of up to £5,000 - they could also face six months in prison.
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