I will agree to disagree with you, guys. This is all subjective, and dependent on what your individual station's target demo is. We're not all exactly gunning for the same listeners, nor should we be. Along with some great, innovative songs, there has been a lot of sub-standard CCM since the mid-to-late 80's. If you believe that the record labels' bottom line is money, then they would embrace any artist who would sell, old or new. If you believe that other stations' bottom line is audience, then it stands to reason that they're playing what their individual audiences' like, lest they lose listeners to the competition. Don't like it? Play something else on your station. If you're right, you'll take some of their listeners.
But airing 20% secular implies that you'd rather take the easy route of playing "family-friendly enough" pop over some great (sometimes older) CCM. Step out of the box, go to the mall, and befriend managers at a music store and at a Christian bookstore. Then ask them which CDs are in constant demand. Out here, ancient CDs from Wes King, FFH, Brooklyn Tab, and others continue to sell because great songs are timeless. Some of them never even got good airplay when they were new. Listeners will not go to your CCM station because they hear Daughtry's or Miley Cyrus' latest. They have the local CHR/AC outlets for that, and I would rather aim to be listeners' first pick.
A station owner has far more freedom than a station employee. Seek His vision, clarify it, sell it to your employees, then run with it as hard as you can. Give your market the identification that "When I want to hear ______, I will listen to ____ (YOUR station, preferably first)." Get out in the public and promote yourself at any event your demo would attend. If you've found great indie acts, then who's stopping you from playing them? Run an all-indie program and see how it goes. Then shamelessly remind the audience who broke the song first (thus, where to go for the greatest new music before any other station plays it).
FWIW, people I meet (including my kids, our little church, and hipper music fans) happen to enjoy acts like FF5, VOTA, Skillet, Kutless, Relient K, tobyMac, Decypher Down, Disciple, Hawk Nelson, David Crowder, Britt Nicole, Jeremy Camp, Switchfoot, Red, Sleeping Giant, Stellar Kart, Manic Drive, Tenth Avenue North, Addison Road, Remedy Drive, etc. They even like some PW from bands like Kutless, Tree 63, Crowder, Chris Tomlin, Matt Redman, Matt Maher, etc. (though generally the more upbeat or harder-rocking versions). Festivals like LifeLight and Creation pack in enough of a crowd to confirm that there must be some demand for these artists. I hate to admit it, but a lot of the Christian music shoved down my throat as a kid did not stack up to these modern artists. Sure, there were a select few great ones (I personally enjoy Larry Norman to Rich Mullins to Stryper), but I hardly think posting my list of really cheesy, bad artists of my youth serves anyone. Then again, this age has many more options (iPods, streaming, etc.), and it really is all subjective.