From your description, you want to display some text on the center of the dounghunt chart, right? I have tested it on my environment, there is no such a property to achieve this in Reporting Services currently. Personally, I recommend you that submit this
suggestion at https://connect.microsoft.com/SQLServer/. If the suggestion mentioned by customers for many times, the product team may consider to add the feature in the next SQL Server version. Your feedback is valuable
for us to improve our products and increase the level of service provided.