On a standard banner it's 3.5 percent to grab the highest rarity in the game - SSR. The highlighted employee will get 1% of the total salary, while the SSR employee will receive 2.5% of the salary from the general pool. Since there is only one highlighted SRR per banner, there is no need to feel bad about reaching pity for a unit you don't desire; doing so only takes 150 pulls. On an awakened banner, where you may receive Awakened Employees (essentially UR rare from other games) the probability is the same as for regular banner - 3.5 percent overall and 1 percent to get the awakened employee.