But you'd need to know if the clients using Stetic in their websites are a representative selection or not of the web at large. Personally, this is the first time I've heard of both Stetic or any of the clients they show in their homepage, but that probably doesn't mean much. I'm dubious though on having a "Mozilla 5.0" identification, since that's probably just "Mozilla/5.0" which is in almost any browser UA string out there.
In any case, other sources for browser usage statistics give a much lower quota to Safari (including mobile). Something around 20%.