Hello friends,
How important is the ratio between followed and no-followed links?
The primary importance is earning organic (natural) links to your site. Both follow and nofollow links are a natural part of the web. If you focus on earning legitimate links to your site, you have nothing to worry about. Whatever the ratio works out as, so be it.
If you engage in manipulative link building practices, then you have to constantly worry about being discovered and penalized. The ratio of follow vs nofollow link is one of many metrics a search engine can examine as a possible flag for guideline violations.