Tor's exit relays, like all non-bridge relays, are listed publicly [0] (by necessity, that's how the client chooses a circuit). You can see in the screenshot of whatever you're using to monitor by GeoIP that Tor traffic already gets counted separately. Of the request counts visible, it's making up at most ~6% of them, which makes sense -- Tor is a pretty poor platform to launch a DDoS from, since the relays are already decently saturated, and you're eating the cost from the circuit building (negligible in the normal web browsing case, but quickly adds up when you're trying to create as many TCP streams as you can).

[0] https://metrics.torproject.org/rs.html#search/flag:exit