I created this query which tracks questions tagged with specific traditions for the past 12 months. Here is some of the data visualized (I've aggregated some of the tags and excluded others in the visualizations, you can see the actual data by viewing the query).
Does this mean that Roman Catholics are the largest user base here? I doubt it. Most Protestants don't tag their questions with specific traditions nor with general tags such as protestantism or evangelicalism (although some do), but rather only with the related theological topic. If anything, it is assumed you want a Protestant response unless you specify otherwise. Even so, this represents the data for the tags I've considered. A more detailed analysis would need to analyze questions without depending solely on tags for the perspective they are looking for, which would undoubtedly yield a much higher number of Protestant questions.
How many total questions have been asked in the past 12 months? 1,912. How many have been considered in this query? Only 534 have been tagged with any specific tradition. The chart below visualizes how few of the questions from the past 12 months are tagged with a specific tradition.
As can be seen, fewer than one-third of questions asked in the past 12 months were tagged with any specific tradition.