Regarding:  "Overall, La Niña is not more common that El Niño—in the historical record dating back to 1950, there have been 25 El Niños and 24 La Niñas (counting this year). However, La Niña often occurs in consecutive winters, while El Niño rarely does."

If the case is 50-50, then for every La Nina-La Nina double dip, would would have to have a El Nino-El Nino event.   Otherwise you could not end up with a 50/50 ratio.  

The reversed years have to end up together at some point

What am I missing in this?  Thanks!