Year after year, there was one bad harvest after another.

Literal

Every-year every-year bad-harvest continuation [copula-だった].

毎年毎年 ('year after year') doubles the temporal adverb for emphasis on repetition — a reduplication common in Japanese. 不作 ('bad crop, poor harvest') is the formal noun, opposed to 豊作 ('bumper crop'). 続き ('continuation') as a noun describes a recurring or ongoing state.