AMC 8 2007 Problem 6

The average cost of a long-distance call in the USA in $1985$ was $41$ cents per minute, and the average cost of a long-distance call in the USA in $2005$ was $7$ cents per minute. Find the approximate percent decrease in the cost per minute of a long- distance call. $\mathrm{(A)}\ 7 \mathrm{(B)}\ 17 \mathrm{(C)}\ 34 \mathrm{(D)}\ 41 \mathrm{(E)}\ 80$