I believe it depends on how much competition there is in your industry as well as how reliable your website is. As a general rule, if you are in a highly competitive industry, you will need more backlinks. In a less competitive industry, you will want fewer backlinks. If your website is not very authoritative, then you will need more backlinks on your website, and if it is very authoritative, then you will need fewer backlinks.
As always, it's imperative to keep in mind that there are a variety of other factors that can affect your search engine rankings, including on-page optimization, the freshness of your content, etc., so these numbers can differ depending on the niche or industry in which you're competing.
