488 drivers in Wales were caught over the drink drive limit in December as part of the Christmas clampdown. In all, 30,718 drivers were breath tested between 1 December 2014 and 1 January 2015.
North Wales Police carried out 15,627 tests with 76 positive, while South Wales Police tested 4,684 with 230 positive.
Dyfed-Powys Police had 8,204 tests with 140 positive, while Gwent had 2,203 tests and 42 positive.
Recent figures show that motorists are more likely to be tested for drink driving in north Wales than anywhere else in the UK.
The study, based on 2012 statistics, shows that, on average, police in north Wales stop 72 out of every 1,000 motorists.
Dyfed-Powys Police came second in the survey, stopping 44 people in every 1,000.
The research also revealed that women were up to five times less likely than men to be breath tested on the roadside.
The survey also found that South Wales Police tested 14 out of every 1,000 motorists, while Gwent Police breathalysed 12 out of every 1,000.
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