Need a formula: Extracting Years from Seconds Since January 1, 0001 12:00 AM

Question

Input: # of seconds since January 1st, of Year 0001

Output: # of Full years during this time period

I have developed an algorithm that I do not think is the

Answer 1

Const TICKS_PER_YEAR As Long = 315360000000000
Function YearsSinceBeginningOfTimeUntil(ByVal d As DateTime) As Integer
    Return Math.Floor(d.Ticks / TICKS_PER_YEAR)
End Function