eElement('a');
            selector.className = 'selector selector-active';
            selector.appendChild(document.createTextNode(elem));
            cluster_sizes.appendChild(selector);
            if (!(elem in selectors.cluster_size)) { selectors.cluster_size[elem] = true; }
            selector.addEventListener('click', e => toggle(e, elem, selectors.cluster_size));
        });

        // Add event listeners for selector controls
        document.getElementById('select-all-systems').addEventListener