I'm 29 y.o., have a Master Degree in Computer Science and Applied Math.
My experience:
C++ - 12 years
SQL - 10 years
GUI Design - 10 years
Database Design - 10 years
Qt - 3 years
Graphic Design (Photoshop, Illustrator) - 5 years
Delphi/Pascal, Lisp, Cobol, Basic/VB, JavaScript/ECMAScript, XML, (X)HTML, CSS - ~8 years, from time to time.
Software Marketing - 7 years.