There is an 'official' European site which has BEV and PHEV: http://www.eafo.eu/vehicle-statistics/m1
It's currently showing the i3 as being the 5th biggest selling BEV in Europe this year. The Zoe is number one with almost 4 times the sales.
It's possible the i3 might have a good monthly sales if the new cars are delivered in one month and / or dealerships take delivery and register cars as demonstrators. However this is probably best thought as an outlier.
