No, the original is correct. It's saying that this will be the case in 2020 (for the sake of argument, over the year of 2020), not over previous years leading up to 2020.
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NotoriozIf It isn't over previous years leading up to 2020, why wasn't 'in' used?"In" was not used because this does not mean only in the year 2020. What the original statement is saying is that rates of depression are increasing such that, beginning in the year 2020 and beyond, it will be a leading cause of death and disability.