25% of orders may be from specific leasing companies but airlines who order the aircraft will be attributed with the orders in the book (however some airlines may well be leasing/financing the aircraft from a bank or other source which and not 'owned').
As Spanners said, many new engines are power by the hour as this represents good economy for most operators and would probably lean me towards the 90% over the 50%, currently we are in a time of aviation production boom which has been contributed to by the variety of financing available for aircraft and engines.