I'd say that overall in individual competitions it's 75%:20%:5% (physical capacities: navigational skills: tactics).
In middle distance maybe 70/25/5 and long and sprint 80/15/5, but I think that it depends more on personal strengths than on discipline. On all the disciplines you can compensate your physical level or orienteering skills if another one is significantly stronger. But you also need to have reached a certain (quite high) level on all of three things to be able to win a race.
As for Relay, it depends even more about the runner and situation of the relay, but for me, in average it would be 75/10/15 because often the courses are a bit easier and you can benefit from other runners if you are tactically good and know how and when to do it.
P.S. Skills means an orienteering technique; Tactics means the interaction with other runners and pacing during the race.
P.P.S. The photo was taken from here.