For many, many years, the standard FOC recommendation was about 7-10%. That was pretty much the default because most broadheads were in the 125-135 grain range and that yielded 7-10% FOC on normal length and weight arrows. Such arrows have accounted for millions of animals over the years, I'm sure.
However, since you asked, by using a standard length hardwood footing on an 11/32 cedar shaft and tapering the last 9-10 inches to 5/16 and using a 175 grain glue on point, I can get 19%, almost 20% FOC. To get more than that, one needs to go to a longer foot, a heavier head, or drill out the shaft and add an internal metal footing/rod.
However, as Bjorn pointed out, when you start playing around with high FOC with wood arrows, you quickly run out of spine, particularly if you shoot a bow over 55# or so and/or have a long draw length.
Your 14.5% FOC is just fine for woodies.