Zenit
The Zenit is a Ukrainian, previously Soviet, expendable carrier rocket. Zenit was originally built in the 1980s for two purposes: as a liquid rocket booster for the Energia rocket and, equipped with a second stage, as a stand-alone middle-weight launcher with a payload greater than the 7 tonnes of the Soyuz but smaller than the 20 tonnes payload of the Proton.
In February 2015, following a year of strained relations as a result of a Russian military intervention into Ukraine, Russia announced that it would discontinue its "joint program with Ukraine to launch Dnepr rockets and [was] no longer interested in buying Ukrainian Zenit boosters, deepening problems for [Ukraine's] space program and its struggling Yuzhmash factory."
Missions: 84
Successes: 71
Partial Failures: 3
Failures: 10
Success Streak: 4
Success Rate: 86.3%