[Plugin: WordPress Stats] – diagram changed over night

Hello,
since yesterday the diagram of the visits has suddenly changed to a strange one: https://www.szek.net/Untitled-2.gif (see a screenshot)

i have updated some plugins 2 days ago, but i don`t remember if Stats was among them or not.

can you please help me with this? i haven`t found any way to change the diagram view back to the normal one.

thanks in advance,
andi