Even the 55% of the electorate in 2008 is questionable ? It is now revealed how the grand son of the pariah from Kerala, the shenanigan Mahahir how he instantly converted million of muslims from Indonesia and southern Phillippines to become not only as voters but also turning these immigrants to become Malays. Just imagine what the true figures would have been if not for that.
To answer your question why in 1955 the Malays formed 85% of the electorate and became 55% in 2008. Well the non Malays got themselves registered as voters when they, almost all of them, did not bother to. Does that answer your question ? Are you aware that at one time in the past the population of the non Malays in the country is even more than the Malays, may be you were not even born then. Now you should know why the Malay population in the country suddenly became the majority, this to just to justify the many marginalization of the non Malay policies the scumbags and parasites in Umno implemented. A good example if the employment of the Malays is 94% when they wish to have them at 100% but the 6% non Malays are employed out of necessity like the dog unit in the police force. Needless to go into the details you should know why ? Now you know why millions of non Malays have immigrated !