The Reference Desk/Blink

I'm a little confused about the Angels. Its said that they feed off of the days not lived of their victims. At the time of Blink the Doctor is a little over 900 years old, and he mentions that he is 1103 in 'The Impossible Astronaut'. So that right there is about 200 years worth of life, plus whatever is left along his lifetime. So my question is, How can the angels be so weak after sending him back in time and feeding off all of his and Martha's potential days?