Most of my traffic ~ 95% of my website (blogspot) visitors come from Google Search, will I get the normal expected CTR?
In rare cases, CTR is influenced by your traffic sources. For example; Most digg visitors don't click on Ads being tech-savvy. MSN traffic click a lot. etc. The major factors affecting CTR are Ad placement, colors used, your site layout, your niche, targetted Ads being served etc. So I think there is nothing you should worry about your traffic coming mostly from google.
I did a report of what traffic sources get what CTR. I found that Google was the worst converting traffic source. Paid advertising was the best converting.