[Beardy]

I think it makes sense to differentiate them, just as you would differentiate them if it was displayed as a graph of "number of hurricanes by category". If you only include the highest category, you miss out on data that might also be useful, for instance whether there have been more category 1 hurricanes compared to category 5.

If it didn't differentiate them and the last category 5 hurricane was 110 days ago but the last category 1 hurricane was 2 days ago, how would you learn about the category 1 hurricane? In your example it would just show hurricane categories 1-5 sequentially all bunched together, so you'd also be duplicating data which wouldn't be that useful.