''Lost'' makes unusual demands on its audience's ability to keep track of a long-term, detailed plot, and not surprisingly has gradually lost viewership, from 15.5 million in the first season to an average of 11 million in its fifth season, which ended on May 13, 2009.<ref> | ''Lost'' makes unusual demands on its audience's ability to keep track of a long-term, detailed plot, and not surprisingly has gradually lost viewership, from 15.5 million in the first season to an average of 11 million in its fifth season, which ended on May 13, 2009.<ref> |