What do all these coins have in common?

Since Clara was born, I've collected coins. Not just any old coins though, nor a particular denomination. Nope, all the coins collected must have her year of birth - 2007. So, in the last 4 years, she's accumulated the pricely sum of £4.88p. Not bad, not bad at all!

Storm, having been born in 2010, a great year for money .. Has £1.23 in coins. Still some time to catch up?? I was surprised to find a 2010 £1 coin today though, so they are about!