Depends on niche and budget. Normally it's enough 2% CTR and to be on first google page. If you have money and a "killer ad copy" there is no problem to get CTR 10% and more.
It depends on what you call a conversion. I've got a PPC campaign for a strictly offline business - they consider a conversion to be somebody looking at their contact details, and get a conversion rate of over 50%. For retailers, a good figure can be anything from 1% - 20%, it just depends on your business. There really aren't any meaningful benchmarks for these things, you just need to keep working to optimise your website. That said, bidding on inappropriate/vague keywords, writing misleading advert text, or landing people on the wrong page on your website can all hurt your conversion rate...
Honestly, this is a bad question Banana does not equal Apple So if I told you I had a campaign with a 10% CTR with a 10% conversion ratio, it really would not matter, because you can never apply this to your industry. There are to many factors that play on conversion ratios and just because someone else can pull off a certain number, it does not mean its something that you should be aiming for. Just ensure your ROI is in place and then continue to improve over time. Don't worry about what everyone else is getting.