More than 4,000 drivers in Pembrokeshire were breathalysed in last year's Christmas drink drive campaign.
Police carried out stop checks throughout the county in a bid to educate people about the dangers of drink driving.
Of 4,005 people who were breathalysed, only 37 were arrested for driving while over the legal alcohol limit.
Of those 13 were found to be more than twice over the legal limit, nine were under 25 years old and six were arrested in the morning.
Inspector Andy Phillips said: "Although we breathalysed more than double the number of drivers only 0.9 per cent of people were found to be driving over the legal alcohol limit. This is an improvement from 1.6 per cent for last year's campaign.
"While this is encouraging it is particularly concerning that so many people were found to be at least twice over the legal limit.
"We would also like to stress that people need to be aware if they are driving the morning after they have been out drinking. One person was stopped at 11am and found to still be over the limit.
"The majority of drivers we stopped were all supportive of our action to keep the roads of Pembrokeshire safe and we thank them for their co-operation."
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