Player contributed lore to an AD&D campaign

One of the neat/cool things about Ben Robbin's West Marches game was that players would share info w/each other.

To me, that was a really cool thing that I wanted to encourage players to do in my campaigns.

When players imagine themselves in the worlds I create, when they expand the lore and come up with their own takes, or share what they experience from their own perspectives, it's like I get to explore my world through their eyes. 

Over the years, I've tried to do entice players to write journals or after-action reports. I then share them either on the campaign website or thru discord or (usually) both. 

But motivating folks to do so has been hard. It'll happen in creative bursts - players get a topic they want to write about, they'll go through a run of stories, and then... it seems to fizzle out.

Maybe I'm not providing enough of a reward?

In the past, I've awarded a flat 100xp per journal entry. Well, that's valuable to a first level PC, but a 4th or 5th level character, that's barely the value of a bit of treasure. Hmm...

So I'm proposing something new to my players -  5% towards their next level amount (i.e., the number they have to hit to gain the next level), capped at 10,000xp per entry? 

For a 1st level mage, that's 125XP, a nice bit. For a 5th level mage, that's a healthy 2,000XP. I don't know if that's enough of a reward to make it worth the effort to write, but I've proposed it to them, so we'll see. 

What do you think? What have you done in your campaign to encourage and reward player contributions to your lore and setting?