Practical Mathematics K12A red-line subway train arrives at a station every 5 minutes and stays for 30 seconds.
A blue-line train arrives on the other side of the platform every 2.5 minutes and also stays for 30 seconds.
I randomly arrive at the station and always choose the train which arrives first, or any of the two if both trains are present.

What is the largest possible percentage of time that I take the red-line train?