For those who are interested in the average viewer per episode through the history of the show, it stands like this:
Season 1 . . . . . 5.23 million viewers
Season 2 . . . . . 6.91 million viewers (+32% from the previous season)
Season 3 . . . . . 10.75 million viewers (+55% from the previous season)
Season 4 . . . . . 13.33 million viewers (+24% from the previous season)
Season 5 . . . . . 14.38 million viewers (+8% from the previous season)
Season 6 . . . . . 13.15 million viewers (-8.5% from the previous season)
Season 7 . . . . . 11.35 million viewers (-13.7% from the previous season)
The trend here is pretty plain.