Hello, its my first time posting in this forum.

In all my life i always thought that the average concept was really natural to me, we have many values, with many ocurrences for each value, we sum each value multiplied by his number of ocurrences, and divide this sum by the total number of ocorrences of values.

This always seemed to be fine to me. Some other day i was talking about leap years, and each year heaving an average of 365.25 days. My question is, we know that in each 4 years 1 of them is a leap year, so (365*3+366)/4 = 365.25

i understand this result, but there's something that seems weird to me, the years dont stop counting, so whats the sense in calculating the average days of all years that existed and will existed basing ourselves in only 4 days?

If the universe only had 5 years, we wouldn't be able to conclude that the average of days by year was 365.25, since we would get (4*365+366)/5 != 365.25

Can someone help me understanding the concept?

Thanks in advance