[avgcorrection]

“This century” is fixed to start at 2000 until 2100, same as this decade is 2020–2029.

“Last hundred years” for the former interpretation.

[Karellen]

Or 2001 until 2101, if you're being pedantic about the Nth century AD/CE.

(Because there is no year 0 in the AD/CE calendar, so the first century in the calendar starts in year 1, the second in 101, etc...)