Syntax
=YEARFRAC(StartDate,EndData,Basis)
Basis : Defines the calendar system to be used in the function.
0 : or omitted USA style 30 days per month divided by 360.
1 : 29 or 30 or 31 days per month divided by 365.
2 : 29 or 30 or 31 days per month divided by 360.
3 : 29 or 30 0r 31 days per month divided by 365.
4 : European 29 or 30 or 31 days divided by 360.