Comment by bell-cot

If you're getting scanned, keep logs, and have a decent way to tag log entries with the associated vuln, then you can start building statistical models of how exploit attempt probabilities fade as the target software gets older and lower market share. No, the 0.1% won't be exact. Yes, such data and models can be shared.

Paying $$$ for a LatestGreatest(tm) Firewall won't make you 100% secure either. And the $$$ might better be spent on an extra layer of swiss cheese, or better recovery capability.