At this link, you can watch the world hacking map, hosted by Norse. Apparently back in 2012, the United States was getting attacked at least 10,000,000 times a day. Can you imagine what it is now? 20 million? 40 million?
Cisco has a whitepaper outlining a strategy to protect against a DDoS attack, because when you think about it, if a hacker fails to exploit any vulnerabilities because a company has fully patched all their systems, they will usually resort to a DoS or DDoS.