By 2013, fuel costs have made smaller 50-seat regional jets uneconomical on many US routes, accelerating the retirement of young CRJ100/200s, and lowering the ERJ-135/145 values.[40] The last aircraft delivered had a value of $22 million, falling to $2 million 13 years later due to their operator concentration in the US.[41] Airlines are replacing their CRJs with more modern and larger airliners like the Embraer E-Jet and Bombardier CRJ700 series.