It was starting to feel like every continuation I file gets a nonstatutory obviousness type double patenting rejection as a matter of course. So I decided to look up the numbers on the prevalence of terminal disclaimers.
Over 25% of continuing applications have a terminal disclaimer
Below is the percentage of continuing applications (defined as having a continuation, continuation-in-part, or divisional in their chain of priority) which have a terminal disclaimer. As you can see it has generally risen each year since 2002 and is up over 25%. The number is actually lower than I expected.
Almost half of continuing applications in TC 2400 (computer networks) have a terminal disclaimer
Below is the same data broken out by technology center. Part of the reason that I expected more terminal disclaimers may be that I work a lot in 2400 and 2600.