Numbers vary depending on the survey and most surveys only include maybe 1/3 of commercially managed hives, to start.

Overwinter losses are probably around your number for the last several years but all-year losses are much higher. The USDA stated for 2013-2014, for example, higher summer losses than winter for the first time, for an annual total of 42.1% *

Regardless of the exact number, my point is still valid in discussing your original question.

[*] http://www.ars.usda.gov/news-events/news/research-news/2015/...