From MD/PhD matriculants between 1995-2000 (matriculated in these years, so graduated generally between 2002-2010), 73% of matriculants graduated with both degrees (2,582 MD-PhD program enrollees, 1,885 MD-PhD graduates). 23.1% of students (597/2582) completed MD graduation (and did not finish the PhD). 3.9% of students withdrew/were dismissed entirely.
86% of students that did not complete the PhD graduated with an MD.
(See
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3874256/)
You are in good company.