 <translate> 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. <yor> Láti dáhùn ìbéèrè tó wà lókè yìí, gbólóhùn tó bá a mu ni: Àkọsílẹ̀ náà wáyé ní ìbẹ̀rẹ̀ àwọn ọdún 1990, ó tẹ̀lé Charlie, ọ̀dọ́langba kan tí kò mọ nǹkankan nípa ara rẹ̀, ní gbogbo ọdún àkọ́kọ́ níléèwé gíga rẹ̀ ní ìgbèríko Pittsburgh. Nítorí náà, ìdáhùn tí ó kẹ́yìn ni ìbẹ̀rẹ̀ àwọn ọdún 1990. 