How old were you when the Whalers left? I was there for the worst 3 seasons Hartford had and frankly there are many worse markets in the league right now who rarely pay full price for their tickets, have worse TV ratings, and often have much better teams..
You could be referring to one of two three-year stretches. I'm guessing it's 1991-92 (65 points), 1992-93 (58 points), and 1993-94 (63 points).
In those three years, Hartford had attendance of 10,832; 10,583; and 10,492. In the 15,635-seat Civic Center, that comes out to averages of 69.3%, 67.7%, and 67.1%.
The following teams have never been below 69.3% in any season of their existence, which Hartford did three times in three seasons:
Anaheim
Atlanta
Columbus
Dallas
Florida
Nashville
Phoenix
I tried searching for Whalers' TV ratings over time, but all I could find was that WHCT carried the team's games. So many people watched that the station went belly-up four years later, and this was when the team was actually doing something resembling contending (1985-89).
Hartford's ratings for the 2010 gold medal game were 17th in the United States, behind Columbus (8th), West Palm Beach (11th), Kansas City (12th), Seattle (14th), and Cincinnati (15th). Expanded 2014 metered rankings weren't released outside the top 10.