Aggregating spatial data with marker clusters

For an Australian client I have developed an interactive map where they are able to see their Financial Planners & Accountants. Because there are a lot of employers that need to be displayed on the map, some clustering is practical. I have decided to use D3js and marker clustering, these are markers that aggregate the datapoints for a certain area. When a users zooms in the markers will fall apart in smaller markers until the marker has size 1. The number inside the markers tells the number of datapoints (employees).

Clusters markers GrowthFocus