According to the Wall St Journal, only 7505 of those sorties were offensive strikes on Libya. That's about one third. Presumably the bulk of the two thirds non-offensive sorties were tanker missions. Sorties are expensive, it takes just as much work, fuel, maintenance, and expensive aircraft to fly a tanker sortie as an offensive sortie.
It's 400 miles from Sicily to Benghazi in Libya which is a bit of a stretch for modern fighters. 400 miles one way, or 800 miles round trip. Back in the day the old F106 could fly from Duluth MI to Tyndall AFB in FL non stop, about 1600 miles. It could do the 800 mile round trip to Benghazi and have a decent loiter time over target without tanking. Apparently the current fighters (all one or two generations more advanced than the totally obsolete F106) don't have the range to cross the Mediterranean and return. You could save a lot of sorties if the fighters had the range to get to Libya and back without tanking.
They report hitting a lot of stuff including 555 tanks and armored vehicles. That's a lot. Erwin Rommel at his best, campaigning in the same area, never had 400 tanks to call his own. Either Qaddaffi has a huge tank fleet, or the pilots are making a lot of far fetched claims.