documents/write-math-ba-paper: added 'relative' to make sure nobody gets confused

documents/write-math-ba-paper/write-math-ba-paper.tex

@@ -44,7 +44,7 @@ variants for multilayer Perceptron training were evaluated using $\num{166898}$
 recordings which were collected with two crowdsourcing projects. The evaluation
 results of these 21~experiments were used to create an optimized recognizer
 which has a TOP-1 error of less than $\SI{17.5}{\percent}$ and a TOP-3 error of
-$\SI{4.0}{\percent}$. This is an improvement of $\SI{18.5}{\percent}$ for the
+$\SI{4.0}{\percent}$. This is a relative improvement of $\SI{18.5}{\percent}$ for the
 TOP-1 error and $\SI{29.7}{\percent}$ for the TOP-3 error compared to the
 baseline system.
 \end{abstract}