A bit more than two notches I'd say. The correlation between those is pretty enormous.
It's funny how a small industry is built around this. I remember a few years ago you could pay a monthly fee and they would have tiers and live support.
It wasn't very pricy for small attacks, sometimes even free for anything under 300 seconds.
I’m sure anyone else in the ISP industry will tell you that anytime kids are off school (summer holidays or half term here in the UK) the DDoS alerts go up a notch or two.