A cement manufacturer has supplied the following data:

Tons of cement produced and sold $680,000$

Sales revenue $ $2,788,000$

Variable manufacturing expense $ $1,156,000$

Fixed manufacturing expense $ $760,000$

Variable selling and administrative expense $ $272,000$

Fixed selling and administrative expense $ $294,000$

Net operating income $ $306,000$

The company's contribution margin ratio is closest to: