I love Freebitco.in
you're really lucky, I ever caught a value higher than 9985...maybe soon
My record is 9988...
I did quite a bit of testing on this and setting the mining at 20% had no noticeable impact on anything I use on a day to day basis. It really is quite odd that anyone could be worried about the impact of using a processor to do processing. As long as it is properly cooled and the safety cutout systems are all working to prevent overheating running at 100% is perfectly safe. Running at 20~30% is just normal usage.
Running mining page now on my computer, 80% of CPU power and i don't notice any lag in my activities (which are web browsing and working on documents, not very CPU-consuming).
CPU now are regulated, if they heat too much, they lower their max frequency to cool down.