Graduates?

[Lord Mordeth]

So i start building my city and all's well, then at some point, regardless of what i do, no more graduates 'spawn', thus my beautiful city is pretty much doomed when my priests/etc start dying off.

Now, i know no one ever reads or visits this forum, but incase someone does.. how the frack can i get more graduates, thus priests, scribes, overseers and whathaveyou in the long run?