The "inflation targeting era" began around 1995 [1]. The official story explaing how 2% became an (informal) international standard is kind of interesting [2].

[1] https://www.stlouisfed.org/-/media/project/frbstl/stlouisfed...

[2] https://www.nytimes.com/2014/12/21/upshot/of-kiwis-and-curre...