EEA PR form benefits

[Witor]

Hello

I live in the UK since 2008. I am in the process of filling in EEA PR form. Part of section 16 (16.2 to be precise) reads:

'please complete the table below to show the amount you/your sponsor receive(s), or received, each week/month and for how long the benefit has been paid.'

I receive or have received working tax credit, child benefit and child credit

I have 2 problems filing this section:
1) I have no clue when my child credit payments have started. How can I find out? My bank statements don't go that far back in time...
2) I can't find any record of working tax credit. Is there a way of finding if I had one, when it started, stopped and how much I was paid? Again I cant find any evidence of that on my statements.
3) Child tax credit and child benefit payments have varied over time. How am I suppose to know which amount i should put per week/month?