Here's a couple of  rather obscure points...

Your calendar is only accurate after October 1582. This is when the switch
was made from the Julian to Gregorian calendar system. In that month the
dates 5th thru 14th were dropped, making the month look like this...


    October 1582
Su Mo Tu We Th Fr Sa
    1  2  3  4 15 16
17 18 19 20 21 22 23
24 25 26 27 28 29 30
31


Also, years divisible by 4000 are not leap years. This will not be an issue
for another 1999 years, but nobody can say Pope Gregory didn't plan ahead!

Greg Engelkemeir