You're looking at the amount of gas in storage indicated by the blue line. The solid black line is the 5 year average, the shaded area is the highs and lows.
As you can see the blue line was well above average last year well into the end of the winter which is huge surplus of gas on the market, this is why natgas has been so cheap recently. It's now returned to the 5 year average and the price will go back up.
You're certainly not going to see prices like you did in 2007 into later 2008 but it will increase. The one big question is how it's going to affect electric rates.