Clives figures are out of date too (early Jan 2016) and don't include the collapse of the Aleppo front (Feb) or Palmrya and its western territory (Mar)
In fairness it is a little difficult to talk in percentages about land lost/ taken, as a vast majority of it isn't disputed (uninhabitable desert). Anbar provinece is a classic example. If you control Ramadi you can present yourself as controlling Anbar, which is a huge swathe of desert. It looks good on a map when you colour it in, but its of little strategic value
The nature of the war is that its not really accurate to talk in terms percentages though, but rather in terms of supply routes (roads in any other language) and the 25 miles corridor either side of them that can be used to attack supplies. Palmrya is significant as it opens up the route to Raaqa. Plamrya also has a heavy lift military airport
The peace talks amongst the rebel opposition have proven interesting too, with the western backed 'moderates' suggesting that Kurds should be exterminated. Russia & the US have been calling for the involvement of the Kurds, but Turkey is blocking it. The Kurds meanwhile have declared their own territory independent from Syria, something which Assad has challenged, and which Putin has warned him not to push his luck over.
As for the Free Syrian Army (remember them?) they were the ones who David Cameron said we should support as recently as December 2015, and that they were 70,000 strong. Well sadly for Cameron, so far as I can gather, they aren't participating because they were defeated 12 months ago and have broken up
http://www.ibtimes.com/four-years-later-free-syrian-army-has-collapsed-1847116
Russia's been the game changer, something widley acknowledged by anyone whose looked at this. To pretend otherwise is plain silly. There has to be a realistic probability that had they not stepped in, ISIL would have over run Damascus and western Syria this year and been perched on the Jordanian border. Heaven knows how many more refugees we'd have heading our way.