How many law firms use MyCase?

I'm curious to know, just how prevalent is the use of MyCase among law firms? I understand it's a popular legal case management software, but I'm interested in getting a sense of the scale. Are we talking about a select few firms adopting it, or has it become a widely-used tool across the legal industry? Can you provide any insight into the number of law firms that have chosen to utilize MyCase for their case management needs?