How many years are in 5 days?

Answer 1

That depends on the dates. If date1 is equal to 2008-Jan-01 and the date 2 is 5 years into the future, the number of days are 1827 days. If date1 is 2005-Jan-01 and five years into the future it is 1826 days. On average there are 365 days / year.
Normally 1825 days but allowing for a leap year there are 1826 days

Answer 2

In a 365 day year, 5 days is equal to 5/365 = 0.01369863 recurring (that is, 0.013698630136986301369863...) years.

In a 366 day year, rounded to three significant figures, 5 days is equal to 5/366 = 0.0137 years.