This page and the
next page provide a nice visual look at relative risks. You can see that although Miami - Fort Lauderdale get reported for the highest city risks, the activity levels in Sumter and its surrounding counties rank among the highest in the nation. Florida leads in deaths by lightning.
[EDIT] page forward to the lightning maps. They are interactive, too, so you can look by county.
Maybe someone can contact Vaisala to see if there is public access to their database, if you want to get raw data for risk calculations.
BTW. Some of the posters need to understand that "lightning" is two syllables, not three. So stop inserting an "e" into "lightning". You are turning it into a word describing a weight reducing activity!