LL Jehto, I admit I didn’t check that fact, but considering this is McLaren they will probably have thoroughly checked it before putting it out in the public. And it makes sense, just think of the championships they won with Lauda, Prost and Senna in the 1980s and early 90s, while Ferrari was in a slump more or less since mid 70′ until the Todt/Schumacher team really got it going only 12 years ago.
The trick is in the wording, while McLaren might have won more since 1966 than Ferrari, Ferrari did a lot of winning since far before that!