thank you for your quick reply.
It is true that in the dimension limits tab I can set the max. number of blocks shown. However, in my case there's nothing set in this tab and QlikView still aggregates block 7 & 8. I also tested using limit to the max. 8 blocks but still no change.
It seems as there's an automatic aggregating function if blocks are having a specific small value.
In my case block 7 & 8 account for 0,89 % of the total sum.