A few figures:

For sites that have set up an advertising referencing campaign, 4% of the traffic would come from this type of campaign. The rate of transformation of an advertising referencing campaign is as good as that generated within the framework of natural referencing.

An advertising referencing campaign also obtains other advantages:

• to obtain immediate visibility on the search engines, in particular on key words selected for natural referencing. In this way, you can compensate for waiting for results that can often be long with natural referencing. 
• to be able to position yourself on the first page on general or competing key words, thus circumventing the difficulty of a similar positioning within the framework of natural referencing.
• to have immediate visibility during specific events (seasonal operations, product launch …) and thus generate traffic quickly. The flexibility of these campaigns also makes it possible to put them on stand-by at any moment.
• to obtain targeted traffic (thanks to a good "expression/announcement/ landing page " agreement)
• to extend your visibility and  reach a precise audience by appearing on partner sites and  content sites of the advertising link platforms.