Delta % in benchmark

Values are in microseconds (μs). The delta is the percentage difference.

For ex. for time if we have Y values like this
```
renctypt: [1, 5, 10]
pyflocker: [1.5, 10, 11]
```
Then our Y will be
```
[50, 200, 10]
```
This is how much percentage slower is.

Will be the percentage difference between them. Same for MB will show percentage difference on how faster is.