The large number in the chart is the temperature of the category.
In the below picture the temperature of the category Team Spirit is 8,8.
The index number is a medium of all answers within Winningtemp users, users in your own industry or organisation (depending on your setting). In the picture below the index to compare with is an industry index of 8,0.
When you hover over the edge of the circle you can see how the responses are divided in this category. In the below example 19 users have given 19 answers with the second happiest smiley (light green smiley).