Checking spelling and grammar for 2 sentences

Hi! can you please check this? I'm not sure about the right use of the words I chose and the grammar of the following sentences:

The Group's fixed rental income increased in 2011 and 2012 (in yearly basis) in average rate of approximately 79% per year. The increase resulted from purchasing of two new assets in Chicago and Ohio and also from "P" project development continuation during the examined period.
The increase derived from new assets acquisition during the period under review and from "Y" project development continuation in Serbia.


1) can I say "Group's fixed rental income " ? I meant to say the revenue of the group from rent income.
2) Can i say resulted from purchasing of ? or should I say acquisition of ?
3) Is it logically "P" project development continuation during the examined period. or I should say "the period under review" and "the continue of the development of P project"?

Regards