I ran into this the other day and thought was interesting. You can see the full study HERE, but here are a few of the points that are worth noticing:
84% of the firms are independent (non franchise)
13% are independent franchises
3% subsidiaries of a national or regional corporation
8 out of 10 specialize in residential RE
13 years is the average time the firms have been around
80% of the firms operate out of a single office
8% of the firms have 4 or more offices
25 is the average number of transactions for the typical firm