Right-branching noun compounds do tend to be more common than left-branching in English corpora. The conversion of CCGbank (a corpus of CCG-annotated Wall Street Journal text; see
http://groups.inf.ed.ac.uk/ccg/ccgbank.html) from the Penn Treebank required imposing binary branching on all noun compounds, and they opted for universal right-branching, given that recovering the correct bracketing was considered too difficult / out of scope, and right-branching at least guarantees correctness >50% of the time.