I really miss this feature from Google search, and regularly bounce back to Google for it.
Option for setting the date range of results.
When searching for tech answers to tech errors, sometimes the most popular (linked-to) results are too old to be relevant, so I change Google's "Search Tools" option from "Any Time" to "Past Year" or "Past Month." A good example of this is looking for answers to tech problem on a new release of an operating system, e.g., Yosemite OS X 10.10.x or a symptom of a new computer virus: you probably don't want result pages from 2007 even if they're most popular page for that search term. I use the date range limitation frequently in Google because website data spans decades.
If DuckDuckGo had the date range option I'd rarely need to bounce over to Google.