From Nielsen ratings:

Lesbian, Gay, Bisexual, Transgender (LGBT)-inclusive programs represented almost a-quarter (24%) of broadcast primetime scripted and reality shows last season, garnering 28% of broadcast primetime TV viewing and over one in 5 (22%) ad dollars, according to Nielsen data released in October 2011. Motion pictures and department stores led all categories driving advertising on LGBT-friendly programming, allocating 28.3% and 27.6% of their ad dollars respectively.

Not far behind, credit cards, telephone, and tech companies also spent a significant share of their ad dollars with LGBT-friendly programs, at roughly 25% each. Of the top 10 overall advertising categories, retail (18.5%) and pharmaceuticals (14.9%) dedicated less of their ad budgets to these shows than they did on the average for all categories.