for a ... what was it? 4.7bil pop? (looks it up)
assuming medium random traffic.... yeah, that's normal. "not a nice system" (the way it works), but normal.
Thing is, you could only raise them by ... say ~4% in such a huge system per day through positive actions - that's without retreat being active.
But, once a retreat is active, they get an automatic -2% / day. (at least, pre-update. but we had a retreat ourselves, smaller system, where that roughly held)
So, at best a +2%/day - if there is absolutely no missions/bounties/explo data for any of the other factions. none at all.
In comes random traffic....
well, long story short:
Even pre-update, when a faction went into retreat in a huge system: to prevent it, you need to pull out all the stops.
including going on murder sprees killing system security, driving passengers into the sun, KWS-ing the nav-beacon hoping for the 1 in 50 that has a bounty from the retreating faction ... the works
and, I'll admit it: I've never attempted such a big feat. The above is mostly theoretical know-how only
PS: that retreat went active on the 15th, right? so, today is the last day to make a difference. if they're below 2.5 tomorrow, they'll be gone Sunday.
good luck! (and, I mean that)