Introduction of CD-R Writing Speeds Support On Media By Year?

I would like to know what year was each writing speed introduced as supported by CD-R media?

1x
2x
4x
6x
8x
12x
16x
24x
32x
40x
48x
52x
56x

I think that 6x was probably introduced sometimes between 1993 and 1994? 8x was probably introduced between 1997 and 1998? 12x might have been introduced sometimes in 1998? 16x might have been introduced sometimes in 1999?