I presume you have an initial value for $x$, and then a later value for $x$, and you want to calculate what percent change you have from the initial value of $x$.
So say you have two values $x_1=.02$ and $x_2=.022$. So as you've calculated, the increase in going from $x_1$ to $x_2$ is $.022-.02=.002$. But $.002/.02=.1$, so there has been a $10\%$ increase in $x$ from the initial value.
The percentage of the difference won't always be positive if your second value of $x$ is smaller than the first. For example, if instead $x_1=.022$ and $x_2=.02$, then the change is $-.002/.022\approx-9.09\%$.
In general, to find the percentage of change, you can use the formula
where $x_i$ is your initial value of $x$, and $x_f$ is your final value of $x$.