I can't remember exact numbers from the article in CycleSport but it's about 60% Campy (brifters/front/rear/derailures). Many of the teams use different cranks and some are using different brakes. Campy still is the majority but that has really come down in the last 10 years.

The thing that amazes me is that after all the time Shimamo has been in the pro peleton it took untill 1999 for them to win a TdF!