The figures I had were 6% average for the past year. There was a high in January of 10%.
It has been voiced that people are buying EVs as an extra car, and that is contributing to the problem. Apart from the lack of any evidence to suggest that, it is also a dumb comment seeing as if that was the case (extra car) then only one car would be on the road at any one time. Even if this were to be the case, such extra cars would surely impact parking congestion, but would have no impact on roadside congestion, and a beneficial impact on roadside pollution.
With regard to roadside pollution, the goal should be to ensuring that 100% of new private cars are EVs. That way, the incremental impact of new cars to roadside emissions will be zero. Not so much stopping new cars, just stopping new roadside polluting cars.
Of course, we all know that the impact of private cars, compared to the dirty commercial and public transportation fleets, is tiny. But, converting the private fleet is an achievable goal (see norway, etc), as the cars are available today. Converting the commercial and public transportation fleets will take investment in charging infrastructure and needs more variety in available vehicles.