Ifo is changing its indicator to include responses from the services sector
And also to rebase the index - whereby the base year will be from 2015, no longer from 2005. The changes will be from this month's reading onward and that means the prior reading (March report) of 114.7 will be revised to 103.2 under the new methodology.
The previous methodology only accounted for manufacturing, construction, wholesaling, and retailing. It only makes sense for them to account for services too, since it contributes to almost 60% of Germany's GDP.