2015 is a year that will be remembered by Apple’s software and security engineers. This is the most prolific year for OS X malware, in history. The threat research team at Bit9 + Carbon Black spent over two months of 2015, 10 weeks to be precise. They discovered five times more malware in 2015 than all the malware samples discovered during the previous five years combined. 2015 will also be remembered as the year of the XcodeGhost, the first instance where a malware had a major breakout in the famously hard-to-infiltrate App Store.”]
Source: https://www.csoonline.com/article/2999816/2015-the-most-prolific-year-for-os-x-malware-ever.html