Correction: "... so far not a shred of solid evidence to substantiate alien visitation" THAT YOU KNOW OF.
If you actually believe that government entities are going to share all the solid evidence gathered during any investigation of a highly controversial topic (terrestrial or otherwise) whose revelation could create mass panic or incite war, then I've got some great swampland in Florida to sell you.
Paranoia is not evidence.
I’ve looked at this subject, especially Roswell, very carefully. And it is clear to me that there is no solid evidence. There certainly are some amazing UFO sightings, but they remain Unidentified Flying Objects.
I’ll give you $1 for your swampland.
Got tin?