Counting Recurring Decimal

The recurring decimal $0.\overline{000001002003004005006007008009...993994995996997999000001002}...$ can be written as a fraction $\frac {a}{b}$ as a fraction in it's lowest terms. $a$ and $b$ are also co-prime positive integers. What is the last 3 digits of the sum of $a$ and $b$ ?

Note : If you think the answer ends in 012, type in 012 Hint : There is a pattern in the decimal arrangement. Look at every group of 3 numbers. The pattern is there apart from at the end