more often than not
Also, often as not. Fairly frequently, more than or at least half the time, as in More often than not we'll have dinner in the den, or Dean and Chris agree on travel plans, often as not. [First half of 1900s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.