Trigger condition - Add (assignee) to 'Current user'

In Trigger conditions 'Current user' has (agent), (end-user), and all agents listed by name.  When I want to create a trigger using condition 'current user' and I want the ticket assignee as the current user, I need to create a separate trigger for each agent.  If (assignee) was also an option, I could make a single trigger for this.