Query to get how many posts each day has?

[Dream]

What would the query be, I want to get how many posts a list of days got starting from today and going back X days. An example of what the list would be

Day Posts
3/3 29
3/2 17
3/1 33
2/28 39
2/27 17

I was able to create a list of timestamps for the days I want to get, but stopped on the query.

PHP Code:

    // make list of days timestamps
    $timestamps = array();
    $day = getdate();
    $day = mktime(0, 0, 0, $today['mon'], $today['mday'], $today['year']); //gets today timestamp
    for ($i = 1; $i <= $how_many; $i++) {
        $timestamps[] = $day;
        $day -= 86400; //86400 is how many seconds a day has
    }