If you need more documents....

Go to amazon and check your order invoices
Log to your email account and do a search for 'invoices, receipts, confirmations, shipping/tracking, or wutev'
my school used to keep tax records and payment records for access online too.

Good, I was going to ask this.

If you have a gym membership, or membership at any sort of facility, Martial Arts, recreational sports, etc. that keep a log of days you come in, use that too.

But I don't want them to know all the naughty things I buy! J/k

I actually printed out my order records (the .csv file) from 2007-current along with a few invoices for each year.

PS: If you shop at newegg.com they also have old invoices available.

Luckily for me I'm a shopaholic and have a bank record for almost every day. My bank statements are 500 pages 0_O