However, despite this high esteem, much television drama of the era does not exist in the archives. The live output was generally not recorded at all, while programming from the 1960s was usually wiped for contractual reasons or perceived as being of no further use. This practice means some series are completely missing, such as "United!", a football-based soap opera which ran from 1965 to 1967. Others have large gaps; "Dixon of Dock Green" has only about thirty of its more than four hundred episodes surviving from its twenty-year run.