I think the 1/3 was reported by the guy in the UK OPM magazines (the first to review the game). Another review (don't remember who) said 40% of the game consists of cutscenes.
No foreign sky protected me,
No stranger's wing shielded my face.
I stand as witness to the common lot,
survivor of that time, that place.
- From 'Requiem' by Anna Akhmatova