What year when written

[Sproket]

What year when written in Roman numerals uniquely contains one each of the Roman number symbols in descending order?

 

[Mikey1]

1666 MDCLXVI

 

[Sproket]

Mikey - correct

(M = 1000, D = 500, C = 100, L = 50, X = 10, V = 5, I = 1.)

= 1666