I was getting around .019% - .03%. Which I thought was awful. Around a dollar a click and targeting all the major programming languages.
Average for FB is around 0.04%. I was paying around 5-10 cents a click. Were you paying CPC ? - if you optimize for CTR I find buying CPM more effective.
Yeah CPC.
Highest CTR was with Perl developers? Are you sure you advertised on Facebook and not Usenet? ;).