No, it has never been more than 3 years old. The only time it was ever over two years old was between July 2004 and June 2005 (due to the infamously-delayed Sarge release). Until 2002, Debian released a stable distro every year. Since Sarge, it has been just under two years between releases.
So in recent years, Stable has always been between zero and two years old, with the mean age being about a year.