NBC?s ?The Voice? did not get the TV ratings it wanted with Tuesday?s finale. The season-ending episode slipped 20 percent in ratings from last year, even though the decline is partly due to the late date. NBC was first in ratings with a 1.8 rating out of a seven share in the advertiser-coveted age demographic of 18 to 49. The channel was also first in total viewers, with an average of 9.8 million, according to preliminary numbers.