Other than that fatal accident in Chiang Mai, so far I am not seeing any information released about the number of drunk drivers caught anywhere in Thailand. They are not even saying if they caught any drunk drivers, much less how many.
I also would be interested to know how many bars really did remain open until 4am, whether customers cooperated with breathalyzer tests or even if the bars tried to administer them, and what, if anything, happened if customers were shown to be above the legal limit.
Theoretically, if all the measures are actually working, then there should be no drunk drivers at all, assuming they did their drinking in bars.
In other words, as of the time of this post we have virtually zero information.