In case the maps are not displayed correctly, please enable flash support in desired browsers
( for example for Chrome: https://helpx.adobe.com/flash-player/kb/enabling-flash-player-chrome.html
Firefox version 49.0.1 - working with Shockwave Flash 22.214.171.124
Firefox version 54 - working with Shockwave Flash 126.96.36.199 ).
For Chrome, also disabling the “Ask first” in Flash settings could be useful.