Ask HN: How can I come up with numerical metrics for my work experience?

Hi, I'm looking to improve my resume in one key area. I've been submitting resumes to many places in my current job search, and have been turned down by some companies considered high-profile for my area.

After getting my resume reviewed, a common theme I get is that my resume is too "boring", it needs to be spiced up with more results from the actions I've added to my bullet points.

Having read a recent article on the common mistakes of resumes, it seems to resonate more with me. I think I'm doing a good job in avoiding most of the resume cliches, but one piece of advice that I can't help but become frustrated with is, to show numbers/metrics.

The problem I have with my resume's experience section is that everyone says that the best thing you can put there is some numerical metric. Like "improved performance of X by Y%" or "boosted sales of X by Y%". It wrongly assumes most programmers have the same impact to the bottom line as salespeople.

At the places I've worked at, the managers don't use empirical data on performance or output of our software. We just build websites and apps for customers and the feedback is answered with a "is it done (and on time) or not done?" or "is the client happy with the changes?".

So when my experience has only been working at places like these, what do you do to show numbers that made a difference in the company?