Sucuri has prepared and released it’s first Website Hacked Report for the first quarter of 2016 (direct link to PDF here). Lots of interesting data points in the analysis of over 11,000 infected websites. This is one of the ones I found interesting:
Almost 10% of the compromised WordPress sites that we analyzed had a vulnerable version of RevSlider. When you combine RevSlider, Gravity Forms, and TimThumb,they account for 25% of the total compromised WordPress sites.