Not 90% la.
More like 75%.

In my division of 100 people, maybe like 25 is perm.
1 M4
2 M3
5 M2
15 M1
3 E6

The rest is mostly E5 and E6 outsource with no chance of promotion of conversion.
Every year is see people come and go. Usually people leave at year 4 when they realised their contract will only keep renewed. And the perm won't leave. Like really. They either love the place so much. Or they don't have place to leave. Like don't see any perm leave in the past 10 years here. Only see they keep getting promoted higher and higher.

No. I'm one of the perm E6 and no I also don't have chance to promote cause too many M1 in my division.