A spinner for a board game has three equally sized sections: an orange section, a purple section, and a green section. If the spinner is flicked twice, there are nine equally likely outcomes (using O for orange, P for purple, and G for green):

S = {OO, OP, OG, PO, PP, PG, GO, GP, GG}

For example, OG refers to the outcome where the first spin lands on orange and the second spin lands on green.

Find the probability that both spins land on the same color.