Average Score Calculation of Contestants

In a math competition, contestants worked on different rational number problems and shared their results. The scores of four contestants were:

Contestant A scored $2.25$ points, Contestant B scored $1.75$ points, Contestant C scored $-1.5$ points, and Contestant D scored $3.6$ points.

What is the average score of these four contestants? Express your answer as a decimal rounded to two decimal places.