Yoruba population 

The 1991 census figure put Yoruba state of lagos at 5.6 million, Oyo state 3.5 million, Ondo state 3.9 million, Osun state at 2.2 million, Kwara state at 1.6 million. Kogi state at 2.1 million. Ogun state at 2.4 million..  Even when satellite picture have show that the fulani/hausa military reduce the population please see google earth links to see the size of the yoruba city of Ibadan said to be 600,000.. While kano said to be 5.6 million.. This show Oyo state would have had over 6 million people.. and also compare Ondo state... which on google you could locate Akure, ondo city, Ado ekiti, and compare it to kano.. 
If the 1991 census figure claim 24 millions. but satellite picture show may be more than that.. and the 36 million estimate is based upon the 1991 census figure.. then if Nigeria only , the yorubas are more than 40 million.. Please note that Edo state also have yorubas living in the north... 

see talk, 1991 census put it 24million inNigeria only,15 years later, 2005 put 36 million in Nigeria only excluding other country... see nigeria 1991census figure, state see how we arrive at figures..