Where hurricances became cat since 1967 when satellites could see them in the sea reliably. This is a copy of this map https://twitter.com/philklotzbach/status/1178137123687284737 by Philip Klotzbach but I couldn't find his code so I made my own. Data from https://www.nhc.noaa.gov/data/hurdat/hurdat2-1851-2018-051019.txt