T1a1 mtDNA

To my understanding, T1a1 mtDNA might have been brought into Europe by the Neolithic farmers. Eupedia states it was found in Cucuteni-Trypillia culture and later on, in Chalcolitic Poland (Corded Ware culture). It also shows up in Unetice culture and even in two samples from Hun, Avar and conquering Hungarian nomadic groups.
But which contemporary population has the most frequent percentage of it? I found different information: that is frequent in the Balkans and also in Western Europe. Possibly linked to Central and East European Jews (Aaron Kosminski which many believe to be infamous "Jack the Ripper" apparently had this haplogroup).