Rather 9.6%?
Let alone the SSRBs (sidemounted boosters) ran for some over 90sec providing the majority of thrust and are jettisoned at ~45km over ground.
The main engine operates from the external tank, carrying 600t of LOX and 100t LH2. LOX was pumped at 1200kg/s, LH2 at 200kg/s.
Doesnt count up to 96% for the "first foot" for me.