I'm looking for something that suggests increasing the cost resulted in people changing their habits. I.e. why government think expanding it is a good idea. I haven't seen anything.
In our family, those who previously drank Coke are still making a point of buying "full fat" and pay the extra, but we were probably not the target as fizzy drinks have always been a once a week treat.
Have people stopped or reduced the amount they buy? Have they switched to sugar free versions? I'm afraid I'm not at all convinced they are preferable for health, or even for obesity.
Apologies, if the data is there I should be able to find it, but I haven't succeeded in that search.