Spam accounted for an average of 84.4% of the total volume of email traffic in the second quarter of 2010. The USA, India and Vietnam were the most prevalent sources of spam during the quarter, whilst the percentage of spam sent from Latin America increased considerably. The highest levels of spam were recorded on 18 April and 9 May at 89.8%, while the low for the quarter was 79.2% on 20 April. The bulk of spam continues to be comprised of emails of 5 KB or less.”]
Source: https://securelist.com/spam-in-the-second-quarter-of-2010/36312/