http://image.ibb.co/bL0OQ6/image.png

There is not really a clarification for the percentage sign. It just shows how well your horse did in that certain area and your horses overall score.

Dressage tests are scored in percentage. That horse wad showed in dressage,and they got 3%

In real life, dressage contests are scored in ...% from 100%
- so a 3% score is quite low!

Each horse startes from the bottom of its level and trains up each week.
Depending on its rating, it will reach 70% or more within 4-12 weeks, then they will start winning their money until they reach 100% at the top of their level.
Then they will level up and start off with low percentage results again etc.