Explanation:

Calculating Age has 2 conditions. Let your Birthday is on January 1st.
1. If the month in which you are born is completed in the present year i.e, your birthday, then
Your Age = Present year - Year you are born 
As of now, present year = 2018
i.e, Age = 2018 - 1995 = 23 years.
2. If the month in which you are born is not completed in the present year i.e, your birthday, then
Your Age = Last year - Year you are born
As of now, present year = 2018
i.e, Age = 2017 - 1995 = 22 years.