The average for an FO (dependent upon base)
Appreciating the rest of your post, this is the main variable, i know a guy based in EDI, made 64K in his first year, longer sectors means more hours and therefore more money per sector. Being based somewhere like STN, some sectors are only 35minutes flying time. and so earnings would be lower.
Some months he makes 3K, some he makes up to 6.6K guess it depends mainly on base.