 "The Choir" produced the number-one single in 2011 and, indirectly, 2015.The most sustained reality-orientated run at the top of the Christmas charts was "The X Factor", whose winner has charted number one or number two on the chart every year from the second series from 2005 to 2014.Bookmakers began to notice the "X Factor" trends in 2007, when, assuming the "X Factor" single would be a certainty for the number one, they started taking bets on who Christmas number two would be instead.