(a) Residential Occupancies. For residential occupancies all 120-volt, single-phase, 15- and 20-ampere receptacle outlets installed outdoors and in bathrooms shall have ground-fault circuit protection for personnel.
When it went into effect was a function of what the local jurisdiction did back then. In my area, the NEC is adopted at the state level, for the entire state, and this happens generally during the summer of the year of the Code.