I edited my comment. I could have been more clear. I should have added that I think it depends on what the creator of the graphics/information is trying to sh

I edited my comment. I could have been more clear. I should have added that I think it depends on what the creator of the graphics/information is trying to show. If it's a pure death rate comparison, then sure you could lump everything together. However, if you want to show a more real-time comparison, you choose to segment the data based on time.