 
<translate> Iji zaa ajụjụ dị n'elu, ahịrịokwu dị mkpa bụ: Edebere na mbido afọ 1990, akwụkwọ akụkọ ahụ na-eso Charlie, onye nọ n'afọ iri na ụma na-abanye n'ime onwe ya, site na afọ mbụ ya nke ụlọ akwụkwọ sekọndrị na Pittsburgh. Ya mere, azịza ikpeazụ bụ mmalite afọ 1990. <eng> To answer the above question, the relevant sentence is: Set in the early 1990s, the novel follows Charlie, an introverted teenager, through his freshman year of high school in a Pittsburgh suburb.
So, the final answer is the early 1990s. 