From my non-professional work experience -- it's 0% of the time.
Most of my time i spent building my own framework or native winapi
(not even one dependency as far only system dll's)
(though LatER it depends how you understand native api, for example i
will probably be using glew and freeglut when developing on
opengl - because i revriting glew seem would be to be boring,
also when i will be doing sound i am not sure if i will stay with
winapi or use some avaliable lib for playing sound)