What is the proportion of active aircraft from CASL (commercial aircraft sales and leasing)? I recently discovered the existence of CASL and I understand they buy a lot of new aircraft (e.g. BOC aviation ordered more than 80 B737's and about 40 A320's few weeks ago). I imagine those aircraft are used for temporary operations (e.g. during scheduled maintenance or waiting for an aircraft to be delivered) by regular airliners, charters, lines with demand growing faster than expected, etc. 

Given the number of aircraft they buy, a significant part of the traffic must be operated by these aircraft. Is there some statistics about the number of aircraft and/or the number of flights performed with an aircraft owned by leasing companies compared to flights performed with aircraft owned by airlines themselves?
According to The Economist data in 2012 showed that:


  Over a third of the world's airline fleet is now rented (see chart)
  and the proportion is likely to keep growing.


The article has some interesting background about the companies involved and the advantages of leasing vs. buying, which one Delta source compares to housing:


  [Delta's fleet planner] argues that big airlines are better off buying planes and keeping
  them for their full lifespan of 30 years or so. Like houses, then,
  buying is cheaper than renting in the long term.