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For accuracy, in pre-covid times it was four per million. Myocarditis is far more likely to be caused by COVID than by the vaccine.

But before January 2021 it wasn't even more likely in people who had covid:

The Incidence of Myocarditis and Pericarditis in Post COVID-19 Unvaccinated Patients—A Large Population-Based Study

by Ortal Tuvali[1], Sagi Tshori[2],†, Estela Derazne[3] [ORCID], Rebecca Regina Hannuna[2], Arnon Afek[3,4], Dan Haberman[1], Gal Sella[1] and Jacob George[1]
[1] Heart Center, Kaplan Medical Center, Rehovot, Hebrew University of Jerusalem, Jerusalem 91905, Israel
[2] Research Authority, Rehovot, Hebrew University of Jerusalem, Jerusalem 91905, Israel
[3] Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv 6997801, Israel
[4] General Management, The Chaim Sheba Medical Centre, Tel Hashomer, Ramat-Gan 52621, Israel

J. Clin. Med. 2022, 11(8), 2219; https://doi.org/10.3390/jcm11082219

Abstract

Myocarditis and pericarditis are potential post-acute cardiac sequelae of COVID-19 infection, arising from adaptive immune responses. We aimed to study the incidence of post-acute COVID-19 myocarditis and pericarditis. Retrospective cohort study of 196,992 adults after COVID-19 infection in Clalit Health Services members in Israel between March 2020 and January 2021. Inpatient myocarditis and pericarditis diagnoses were retrieved from day 10 after positive PCR. Follow-up was censored on 28 February 2021, with minimum observation of 18 days. The control cohort of 590,976 adults with at least one negative PCR and no positive PCR were age- and sex-matched. Since the Israeli vaccination program was initiated on 20 December 2020, the time-period matching of the control cohort was calculated backward from 15 December 2020. Nine post-COVID-19 patients developed myocarditis (0.0046%), and eleven patients were diagnosed with pericarditis (0.0056%). In the control cohort, 27 patients had myocarditis (0.0046%) and 52 had pericarditis (0.0088%). Age (adjusted hazard ratio [aHR] 0.96, 95% confidence interval [CI]; 0.93 to 1.00) and male sex (aHR 4.42; 95% CI, 1.64 to 11.96) were associated with myocarditis. Male sex (aHR 1.93; 95% CI 1.09 to 3.41) and peripheral vascular disease (aHR 4.20; 95% CI 1.50 to 11.72) were associated with pericarditis. Post COVID-19 infection was not associated with either myocarditis (aHR 1.08; 95% CI 0.45 to 2.56) or pericarditis (aHR 0.53; 95% CI 0.25 to 1.13). We did not observe an increased incidence of neither pericarditis nor myocarditis in adult patients recovering from COVID-19 infection.