When did the Colt 1991 Commanders first appear?

[The Real Hawkeye]

I was thinking of buying a new Commander, but want to only buy one recently made, as I understant Colt's newest guns are their best in a while. If I buy a 1991 Commander, am I sure to get a recently made one, or do I need to take note of the serial number to be sure it was made in the last two years? If so, what serial number marks the beginning of the good ones? Thanks.