OK, I've really wasted some serious time putting this one together!
Boeing delivered their first widebodies (747s, of course) in 1969. Since then and up till the end of last year they have delvered 2929 widebodies.
(1380 747s, 947 767s and 604 777s)
1293 had GE (44.1%)
1194 had PW (40.7%)
444 had RR (15.1%)
By engine (i.e. x4 for the 747 and x2 for the 767 and 777)...
3844 PW engines (44.6%)
3496 GE engines (40.5%)
1282 RR engines (14.9%)
(The above does not include engines sold as spares as I have no means of counting them.)
So, GE have powered the most Boeing widebodies but PW have hung the most engines on Boeing widebodies. Clearly, that will change in the next few years.
Graphs to follow...