ActiveAdmin: access to the result of filters
<p>I want to display few stats on top of an ActiveAdmin index page. </p>

<p>Let's say I have a car model, with a color attribute and a year of fabrication. On the top of my index page, I want to display the count of red cars. But I want that count to reflect the use of filters; if I choose to show only cars built in 1995, I want the red car count to change accordingly.</p>

<p>How can I access the filtered list? I guessed the existence of a variable containing the result of filter action, but I can't find it. </p>