Please answer a question about the following article about Post-punk:

During the initial punk era, a variety of entrepreneurs interested in local punk-influenced music scenes began founding independent record labels, including Rough Trade (founded by record shop owner Geoff Travis) and Factory (founded by Manchester-based television personality Tony Wilson). By 1977, groups began pointedly pursuing methods of releasing music independently , an idea disseminated in particular by the Buzzcocks' release of their Spiral Scratch EP on their own label as well as the self-released 1977 singles of Desperate Bicycles. These DIY imperatives would help form the production and distribution infrastructure of post-punk and the indie music scene that later blossomed in the mid-1980s.

When did releasing music indepentently really hit popularity?
1977