This table shows how much XP you can expect to get from a node you wrote, as its reputation rises.

The numbers along the top are the reputation of a node. (This number fluctuates as other monks up-vote and down-vote the node. You hope it only goes up!)

The numbers down the left side are $NORM, explained in Voting/Experience System.

For illustration purposes, look at the last row, where $NORM is 10. If you have a node which has a reputation 21, you can expect that you've gotten about 9 XP from that node. Of course, it's not accrued to you all at once; XP from node rep is allotted as the node's rep changes. And you may not have gotten exactly 9 XP from that node; perhaps the node has been around a while, and some of the voting on it occurred when $NORM was 9.5, or even lower. In that case, you may have gotten more than 9 XP from it.