ten months after the event, what percentage of the participants in a Dutch study falsely remembered watching tapes of a cargo plane crashing into an apartment building?

No one, truly or falsely, remembered watching tapes.

Explanation:

The Bijlmerramp happened in 1992. After the crash of the EL ALcargo plane into an (Bijlmer) apartment building it was soon discovered that the plane was not carrying flowers and so on but military equipment - and even uranium! - for Israel.

At the time I was living in the Netherlands and I don't remember any tapes or studies. I do remember that the Dutch authorities were trying unsuccesfully to cover everything up