There are 4 skin packs missing, except for the first one. Only the 1st birthday skin pack is available when you click on the link to the skin packs.

List of links:

1. https://www.minecraft.net/en-us/pdp?id=8e78a44d-0c1f-4ce2-826b-8bbc555012de
2. https://www.minecraft.net/en-us/pdp?id=02b54955-9b4d-40cb-9b73-360d23cf1b9e
3. https://www.minecraft.net/en-us/pdp?id=603d6be1-7745-4ad8-8af3-908ad017500f
4. https://www.minecraft.net/en-us/pdp?id=a2a7ad5c-f55e-44ff-9f70-a5ae1db821b4
5. https://www.minecraft.net/en-us/pdp?id=cc1e1b86-1863-4c1c-9103-b82b2b70a74b