I'm not saying the graph is the best graph ever, I'm saying it's far from the worst I've seen.

Its also clearly not a line of best fit, as it isn't trying to "fit" the data. It's a trend line that's a vertically offset line from lowest to highest. It's a stupid line, but being used to convey how much growth their has been.

The only real issue with this graph is the information/context being ommited. We know there is a lot more to the autism debate beyond just the rate of diagnosis.