I am looking for a way to visualize credit rating stability results.
Per rating class (e.g. AAA, AA+, AA, AA-, A+, ...), I look at the percentage of obligors that keep their rating from one year to the other. E.g. if in rating class BBB, I have 100 counterparts at
t, and, of these 100, only 85 remained in rating class BBB at time
t+1, the percentage of obligors that keep their rating from
t+1 is 85%.
Doing so, I get a table like:
t to t+1 t+1 to t+2 ... t+n-1 to t+n AAA 80% 90% ... 85% AA+ 75% 92% ... 85% ... Caa 60% 55% ... 67%
To visualize this, I tried line graphs for each of the rating classes, but this way I end up with way too many graphs; it becomes very messy. I thought about grouping the ratings into broader classes but I lose some information this way.
Does anyone know about a good visualization technique for this kind of problem?