Is that measured in suicide attempts, or successful suicides? Because if it's successful suicides it might just be that the number of attempts is the same, but they have more effective methods of killing themselves, like pesticides:

https://80000hours.org/2018/03/leah-utyasheva-pesticide-suic...

(I know Sri Lanka isn't France, and we cannot assume anything about French pesticide laws. I'm just offering another possibility)