Here is Burhan Ghalioun, former head of Syrian National Coalition on the percentage of Islamists among the rebels

This was in 2011, December: "Mr. Ghalioun: I don't think there is a real fear in Syria of a monopoly of Islamists—not even 10%. In this regard, Syria is different than the other Arab nations. The Syrian Muslim Brotherhood has been in exile for 30 years and their internal coordination is non-existent. The people who are protesting and society in general, are pious. But not every Muslim is an Islamist. This is a big mistake [in perception]. Being someone who prays or fasts doesn't mean you want an Islamic state. Islam in the form of the Iranian state has been defeated in the Arab world. All Islamist movements now want to copy the Turkish model."