The US Congress may have declared this the year of the blues, and a new PBS series focuses attention on the music. But “you rarely hear a blues song on the radio, and it’s hard even to find the CDs in stores. Sales of blues records this year dwindled to only 1 percent of the US market, according to Nielsen SoundScan figures. Yet fans and industry insiders are hoping against hope that a change is coming. Can you say ‘blues revival’ one more time?”