I think I've discovered the culprit. Dense surface roots from a nearby maple tree aren't allowing the bulbs to grow enough to produce flowers (found this little tidbit on the internet http://www.daffodilmn.org/faq.htm#t1). Looks like I'll have to dig them ALL up and replant elsewhere. Oh joy! :(

Here is a link that might be useful: Daffodil Society

99% of my daffodil bulbs have no flowers, just lots of greenery.

There are numerous reasons why daffs don't bloom, but the 2 most common reasons are (# 12 at the link below) that they are crowded and needing digging (at the 'proper' time of course if possible) or (#6 at the link below) that the foliage has been cut off too soon from the previous year. Leaving the foliage in place to die back naturally is what replenishes the bulb for the next spring season's bloom.

I suspect yours are crowded.

chemocurl...aka Sue

Here is a link that might be useful: 12 reasons why daffs don't bloom per The American Daffodil Society.