That chart does not look reassuring. The infections in or related to dorms only showed up at the start of April, presumably in part because they started mass-testing those workers around then. The number of non-imported cases has been going up exponentially for much longer than that. Also, they're likely to have a much higher detection rate for those workers than everyone else right now given that's where testing attention is focused, so they probably make up a much lower proportion of actual infections than the figures suggest.