9 years old now in 2023 - what year born?

Today, 26 September 2023 if a person is 9 years old now, what year was he born? See below:

If 9 years old, year of birth is:
2013 or 2014*

*It depends on whether he was born before or after 1 January 2014.

If now 9 years and his year of birth 2013 if he was born after 26 September 2013 until 31 december 2013 inclusively, and his year of birth is 2014 if he was born from 1 January 2014 to 26 September 2014.

Other examples:

If now 4 years, year of birth 2018 or 2019
If now 18 years, year of birth 2004 or 2005
If now 21 years, year of birth 2001 or 2002
If now 74 years, year of birth 1948 or 1949

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