I've been putting the majority (nearly all) of my level points into my character's Toughness and tracking their resistance percentages, and something about the percentage number is confusing me.

When the character was 9th level their resistance numbers were such:
Physical: 248.8, Toxic: 248.8, Rend: 323.7
Fire: 255.9, Frost: 255.9, Lightning: 255.9
Aether: 248.8, Sacred: 248.4, Shadow: 248.4

With 255.9 points for Frost, the percentage was 35.8.
With 323.7 points for Rend, the percentage was 41.5.

Now the character is 16th level and their resistance numbers are such:
Physical: 511.0, Toxic: 511.0, Rend: 574.9
Fire: 603.5, Frost: 552.9, Lightning: 552.9
Aether: 489.0, Sacred: 489.9, Shadow: 489.0

With 552.9 points for Frost, the percentage is 40.5
With 574.8 points for Rend, the percentage is still 41.5

The Rend percentage greatly confuses me: is there a percentage cap on the game, in general, or the beta, specific? If not, shouldn't those percentages be rising (in the case of Rend) or maybe rising more (in the case of Frost)?

If anyone has an answer, or thought, please let me know.

Thank you!