There are a couple of keyframe-copy scripts on AEScripts, notably Easecopy and Paste Multiple Keyframes. I don't know how they are storing the copied keyframe information, but you could ask the authors if they can be used for this purpose.
Re: the OP and the way-back-when post.
If you add an expression to the animated attribute but just let the default expression stay, then select all the keyframes and right click on one of them and choose "keyframe assistant", then choose "convert expression to keyframes", you will get keyframes for every frame, select them all (they are usually already selected at this point). Hit copy - because its all keyframes it will include the easing data.
Then that can be pasted to Word or Excel and parsed to columns of data.
Sometimes you have to let Word do some search and replace to convert double spaces to comma's etc so you have a comma, or space, or tab delimited table of values that Excel will like.