Customized bar chart tooltip on map

Hi Community

I am trying to make a report page as tooltip on a map. My problem here is that the report page is going to contain a bar chart that is a little bit customized. let's say our measure is number of banks in each country, basically i wanna rank the countries by number of banks the result is for example this:

1-USA 

2-Canda

3-Japan

4-France 

...

when the user hover over japan for example the bar chart is going to diplay the number of banks of Canada-Japan-France means the country in question the country right after and the country just before.

I hope I was clear in my description