Data ONTAP Release History

I would like to know the release history of Data ONTAP.

Does anyone have any information about these ONTAP's release date ?

  - Data ONTAP 5.0

  - Data ONTAP 5.3

  - Data ONTAP 6.0

  - Data ONTAP 6.3

  - Data ONTAP 7.0

  - Data ONTAP 7.3

  - Data ONTAP 8.0