Sentence Correction (SC) | A new Johns Hopkins study that analyzed cancer incidence by birth year

As a matter of fact, both "are increasing" and " have been increasing" are incorrect. This verb occurs within another verb ("found") that occurred in the past. Therefore this verb should be "HAD been increasing".

Now to answer your question, the word " since" calls for a perfect tense. (but as stated above, here the verb should be in past perfect continuous, not in present
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