This code count the letters but i don't want it to rewrite the same letter twice. What can i do?

```
d=list('banttnay')
for letter in d:
    print letter, d.count(letter)

```

Output:

```
b 1
a 2
n 2
t 2
t 2
n 2
a 2
y 1

```

I don't want it to rewrite 'a 2' or 't 2' twice