Its hard to quantify this exactly. At least according to this article the (mid-term) damage in global economic growth was about 2 trillion USD (https://www.washingtonpost.com/business/economy/a-guide-to-the-financial-crisis--10-years-later/2018/09/10/114b76ba-af10-11e8-a20b-5f4f84429666_story.html). Anything reasonable near that number counts. If you have better ideas to measure this, comment below.