I've just been looking at weekly graphs since 1st Jan 2012, I wish I hadn't!
I combined about 40 sites' data into one and Week 13, i.e. Sunday 1st April onwards, I saw a very evident downwards traffic and visitor trend. Ok, that was Easter week however it has never recovered to its previous numbers and overall it's looking like a 20% reduction in page views and uniques, maybe a little more than 20% and this is my busiest time of year.
Thanks G, have you given that traffic to all the scrapers?
When was the last Panda/whatever iteration?