Below is a graph of the number of prefixes announced into the global routing table which are for unallocated IPv4 space. I had to use the natural log because normally the number is in the 100s, however around 2010 there were days where we had 80,000+ prefixes injected. From late 2007 onwards, we've seen some large excursions and sudden policing activities.
Over the past year, the number of advert'd prefixes has been increasing. As IPv4 space usage expands to fill all allocated RIR-space, will we see even more excursions?
Granted, we hopefully won't see anything like the attacks back in 2010.
The script used, csv data, and larger chart are available over in my project space.