Fractional frequencies in decision tree viewer

In Decision Tree Viewer I get fractional frequencies (e.g., 89.596 of 105.3) assocated with many class values.  I expect integers because the frequency is the number of training examples in the partition matching the split criteria, isn't it?  I apologize if this is a well-answered question or if I am missing something fundamental. 



This is because some of your attributes contain missing values and those are equally split between different branches of the same attribute. This may result into this fractional frequencies that you see in the decision tree view.