Remove comma before Year in Nav of List-View

Hi,

we like your Plugin so much and almost everthing works great. There is just a small issue. We cannot remove the comma in the navigation of this list view https://www.frank-hielscher.de/termine/ As you can see, there is a comma “Januar – Februar, 2017” after Februar with is not correct for dates in german. Could you please tell us, how to remove this?

Thanks & king regards
Michael