Rather than a raw number of XP's for a campaign, I'd rather talk in XP's per daily session.
I use to grant my players with 10 to 15 XP's for this daily run with up to 5 additional XP's. Then each time one part of the campaign is completed the gain goes up to 30 to 50.
As my players usually need around 5 daily sessions to end up one part of the campaign, they may expect up to 100 to 120 XP's ; the more the parts in the campaign, the more the benefits. Usually, I end the campaign after 3 parts, hence leading to ar.400 XP's...
... and even with such "low" gains I consider the PC's are developing too fast and do cope too easily with the hazards...