Pretty much all of them. http://phonetic-blog.blogspot.com/2010/11/vowel-inventories.html http://phonetic-blog.blogspot.com/2010/11/vowel-inventories.... says t

Pretty much all of them. http://phonetic-blog.blogspot.com/2010/11/vowel-inventories.html http://phonetic-blog.blogspot.com/2010/11/vowel-inventories.... says that the average number of vowels in a language is just below 6, and "large" vowel inventories are of size 7-14.