CW would commit hari-kari if their median age was over 40! Here's a HuffPo article that gives the stats.
For years, these networks (except for CBS) have sold advertising based on how many people were watching in the 18-to-49-year-old demographic. Both CBS (55) and ABC (51) had median ages above that range last season, according to the report. NBC's median age was 49 and Fox's was 44.
Among broadcasters, the small CW network specifically targets young women and has a median age of 33