Form I-134, question 2 (K-1 fiance visa)

[vtnh]

On question 2 of form I-134, they asked for the date that I've been resided in the United States. I forgot the exactly date that I arrived in the United States because it's been a long time. Where or with which agency that I can find out this information? I don't want to fill-in the wrong information. I would appreciate for any suggestions from you.
Thank you,
Victor