Hi Coral,
Looking at it another way ......
Improving something by 15 percent doesn't sound like that "tough of an achievement" when put in that context !!!
Maybe I'm "just glowing" from all of that "demineralized (distilled) water" that I have handled over the years putting it in my batteries and radiators !!! See "Duck's" post !
But I couldn't resist !! Have a great day,
Lee