Published earlier this year, this "landscape assessment" combines a literature review of the subject matter with in-depth supporting analysis of data from RAND's Mass Attacks Defense Toolkit.
If you work in the field, there's nothing really surprising here, but it does offer a lot of well-documented hard data to support your security discussions. There is so much sourcing, I think just about anyone will find something new for reference. If you don't work in the field, the hard data dispels some common myths about mass attacks.
If you have an interest, but don't work in the field, the chapter on security budgeting could probably be skipped, but I think you'll find the rest to be a solid read. For the professionals, this is a brief read that shouldn't be passed over.