1 years old now in 2022 - what year born?

Today, 6 December 2022 if a person is 1 years old now, what year was he born? See below:

If 1 years old, year of birth is:
2020 or 2021*

*It depends on whether he was born before or after 1 January 2021.

If now 1 years and his year of birth 2020 if he was born after 6 December 2020 until 31 december 2020 inclusively, and his year of birth is 2021 if he was born from 1 January 2021 to 6 December 2021.

Other examples:

If now 7 years, year of birth 2014 or 2015
If now 14 years, year of birth 2007 or 2008
If now 23 years, year of birth 1998 or 1999
If now 42 years, year of birth 1979 or 1980

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